text:
# Function Pointer as argument nightmare ('&' requires l-value)

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As the title states, I'm getting a "'&' requires l-value" error from the following code:
void InitTitleScreen();

void CSystem::PlayMovie(const char *filename, void *func(void))
{
//TODO: Play movie ....

//Call the end-function at the end of the movie
*func();
}

void CSystem::GameLoop()
{
switch (g_nGameState)
{
case STATE_INITIALIZATION:
{
PlayMovie("data\\Intro.mov", &InitTitleScreen());
}
break;
}
}

void InitTitleScreen()
{
MessageBox(NULL, L"TEST", L"Function pointers suck...", MB_OK);
}

The line that is giving me the error is:
PlayMovie("data\\Intro.mov", &InitTitleScreen());

I've read and re-read tutorials on function pointers ... and can easily do it in C#, but I want to do it in C++ and it is just a little frustrating. The way I'm seeing it, &InitTitleScreen() is the address of InitTitleScreen(), and I pass that to the PlayMovie function, which then calls the function through the parameter. I know that the "l-value" thing means that there is no value to assign from that, but that doesn't make sense, because shouldn't the function have an address? I also tried doing the following:
void *FuncPtr = &InitTitleScreen;

but that didn't help me much either ... just more errors...

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Quote:
 Original post by jonathanplumbThe way I'm seeing it, &InitTitleScreen() is the address of InitTitleScreen()
InitTitleScreen() is not a function. InitTitleScreen() is a function call. InitTitleScreen is a function.

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if I change the call to
PlayMovie("data\\Intro.mov", &InitTitleScreen);

I get the following:
error C2664: 'CSystem::PlayMovie' : cannot convert parameter 2 from 'void (__cdecl *)(void)' to 'void *(__cdecl *)(void)'

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Try replacing "void *func(void)" with "void (*func)(void)"

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Quote:
 Original post by HodgmanTry replacing "void *func(void)" with "void (*func)(void)"
Actually, I'd recommend changing it to boost::function<void ()> - it's more readable (in my opinion) and it's more flexible, too!

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I'm not sure what that "boost::" is, but I fixed it by doing the following:

Changed PlayMovie() to the following:
void CSystem::PlayMovie(const char *filename, void (*func)(void)){	//TODO: Play movie ....	(*func)();}

Changed GameLoop() to the following:
void CSystem::GameLoop(){	switch (g_nGameState)	{	case STATE_INITIALIZATION:		{			PlayMovie("data\\Intro.mov", &InitTitleScreen);		}		break;	}}

and InitTitleScreen() didn't change. I think it was just a problem with my parenthesis not in the right place, making some odd typecasts or something.

Thanks for the help. Now off to learn OpenGL --

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Quote:
 Original post by jonathanplumbI'm not sure what that "boost::" is, but I fixed it by doing the following:

boost is a great big bunch of C++ awesomeness. It's got a whole bunch of neat stuff, including smart pointer classes, cross-platform threading/synchronization, cross-platform file system classes, serialization, networking, regular expressions, and more. Certainly worth checking out.

Codeka was talking about boost::function which lets you create function objects for use as callbacks. You can also combine it with boost::bind to create callbacks to class member functions, which is really neat.

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I know I'm late, but I bet that the reason you got the error is because you typed &InitScreen instead of InitScreen (when parenthesis are not used it becomes a pointer to the function).

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Quote:
 Original post by jonathanplumbvoid CSystem::PlayMovie(const char *filename, void (*func)(void)){ //TODO: Play movie .... (*func)();}

Since you cannot pass functions as arguments (only function pointers), the asterisk in parameters is optional.

It is also optional when you call a function through a function pointer -- in fact, it is even more natural without the asterisk, because calling "normal functions" does a silent conversion to a function pointer first before calling the function anyway -- but that detail is not so important :)
void CSystem::PlayMovie(const char *filename, void func()){	//TODO: Play movie ....	func();}

This SHOULD work, but I haven't tested it. Please confirm.

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I've testet it and it works well.

Anyway @OP you should really consider to take a look at boost.

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Quote:
 Actually, I'd recommend changing it to boost::function - it's more readable (in my opinion) and it's more flexible, too!

Quote:
 ... Anyway @OP you should really consider to take a look at boost.

I know GD.net posters are in love with boost. It's a good library, and I have used it many times.

However, I think far too often people here recommend boost for things far to trivial to matter.

Here you're recommending using boost instead of a function pointer.
"boost::function<void ()> func" vs "void func()" or "void (*func)()"
1st: It makes boost a requirement.
2nd: Any programmer than knows boost should first be familiar with function pointers.
3rd: It's actually far more characters, less readable (IMHO), and slower-compiling than a basic function pointer.

If the extra function pointer functionality that boost provides was useful in this situation, I'd have no problem with recommending it. But, here, it's not.

All I want to say is, boost isn't ALWAYS the optimal solution. Don't just recommend it everywhere you can out of habit or whatever.

I'm only saying this because I see this type of thing far too often here.

And again, don't get me wrong, boost is a good library and I use it when I need it.
And OP, don't let this put you off boost, either.

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Did you know that C++ also allows Function References? Just as you'd expect it's the same difference as between a pointer and a reference, for any other type.
It's not very commonly used but it makes the calling syntax nicer.

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Quote:
 Original post by yacwroyHere you're recommending using boost instead of a function pointer."boost::function func" vs "void func()" or "void (*func)()"I don't see any advantage, and I see a few disadvantages.1st: It makes boost a requirement.
Boost is a requirement of modern C++, unless you can adequately demonstrate why it is not feasible in your situation (i.e. platform compatibility or corporate restrictions).
Quote:
 2nd: Any programmer than knows boost should first be familiar with function pointers.
Every programmer who uses std::map should know how to implement a balanced red-black tree too - but you don't see anyone recommending they learn that first, do you?
Quote:
 3rd: It's actually far more characters, less readable (IMHO), and slower-compiling than a basic function pointer.
Less characters? Really? Every programmer should be a proficient typist, *regardless* of all other considerations. Modern IDEs also include both auto-completion and syntax highlighting, as well as modern compilers with decent performance.
Quote:
 If the extra function pointer functionality that boost provides was useful in this situation, I'd have no problem with recommending it. But, here, it's not.
Who is to say it won't be useful soon? After all, it is only a matter of time till the OP wants to use a member-function as a callback, and then the function pointer approach dies a horrific death.

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Quote:
Original post by swiftcoder
Quote:
 Original post by yacwroyHere you're recommending using boost instead of a function pointer."boost::function func" vs "void func()" or "void (*func)()"I don't see any advantage, and I see a few disadvantages.1st: It makes boost a requirement.
Boost is a requirement of modern C++, unless you can adequately demonstrate why it is not feasible in your situation (i.e. platform compatibility or corporate restrictions)
No way. Boost provides tools for those that need them. I'd guess less than 1/2 of the C++ apps released this year used boost. It is a million miles away from being a requirement.

Quote:
Quote:
 2nd: Any programmer than knows boost should first be familiar with function pointers.

Every programmer who uses std::map should know how to implement a balanced red-black tree too
Eh?
Function pointers are an integral part of C++. Red-black trees are a special case of weighted binary tree that only people who plan on writing their own binary tree might need to know. 99% of coders probably haven't implemented a binary weighted tree themselves. However, the number of C++ users that haven't used function pointers is going to be like 20%, if you exclude all those just past hello world.

Quote:
Quote:
 3rd: It's actually far more characters, less readable (IMHO), and slower-compiling than a basic function pointer.
Less characters? Really? Every programmer should be a proficient typist, *regardless* of all other considerations. Modern IDEs also include both auto-completion and syntax highlighting, as well as modern compilers with decent performance.

I didn't mean it was a problem to type. Number of chars is about readability. And in many cases long lines can lead to multiple lines, especially in function declarations.

Quote:
Quote:
 If the extra function pointer functionality that boost provides was useful in this situation, I'd have no problem with recommending it. But, here, it's not.
Who is to say it won't be useful soon?

Why not just #include every useful library in existence as it might be useful soon. The fact that it might be useful soon, as many other things might, is no reason for using them now. And it's not useful yet.

Quote:
 After all, it is only a matter of time till the OP wants to use a member-function as a callback, and then the function pointer approach dies a horrific death.

Why? Pointers to member functions exist and work fine. And that's all you need for callback. The syntax gets slightly messy, but it's still fewer symbols than the equivalent boost syntax.

And apologies for hijacking the thread and starting what looks like a flame war. I wasn't trying to diss boost, just saying it's not the best answer to every question that it can answer.

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Quote:
Original post by yacwroy
Quote:
 After all, it is only a matter of time till the OP wants to use a member-function as a callback, and then the function pointer approach dies a horrific death.
Why? Pointers to member functions exist and work fine. And that's all you need for callback. The syntax gets slightly messy, but it's still fewer symbols than the equivalent boost syntax.
My point was that you can't define a single function pointer that will accept both free functions and member functions.
Quote:
 And apologies for hijacking the thread and starting what looks like a flame war. I wasn't trying to diss boost, just saying it's not the best answer to every question that it can answer.
The bigger issue I was hinting at, which you seem to have missed, is that nobody in this thread actually suggested Boost - let alone that you should rewrite your code to use boost::phoenix.

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Quote:
 Original post by swiftcoderEvery programmer who uses std::map should know how to implement a balanced red-black tree too - but you don't see anyone recommending they learn that first, do you?

COME ON! I've used std::map and I don't know what a red-black tree is.

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Quote:
 Original post by swiftcoderThe bigger issue I was hinting at, which you seem to have missed, is that nobody in this thread actually suggested Boost - let alone that you should rewrite your code to use boost::phoenix.

Quote:
 Original post by megamoschaAnyway @OP you should really consider to take a look at boost.

Quote:
 Original post by CodekaActually, I'd recommend changing it to boost::function - it's more readable (in my opinion) and it's more flexible, too!

Hmm... looks like you haven't. Anyways, I agree, boost in this case just adds confusion, requires learning a new library, will add size and compile time to his project, all for no gain. Not saying boost doesn't have it's place in code, just saying not in all code. Anyways, OP has gotten it working and has moved on. On the contrary, I recommend the OP learn boost at some point, just not for this.

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Quote:
Original post by m3mb3rsh1p
Quote:
 Original post by swiftcoderEvery programmer who uses std::map should know how to implement a balanced red-black tree too - but you don't see anyone recommending they learn that first, do you?
COME ON! I've used std::map and I don't know what a red-black tree is.
That is exactly my point - yacwroy is suggesting that everyone should know how to implement std::tr1::function before they use it, but the same does not hold for other elements of the standard library.
Quote:
Quote:
 Original post by swiftcoderThe bigger issue I was hinting at, which you seem to have missed, is that nobody in this thread actually suggested Boost - let alone that you should rewrite your code to use boost::phoenix.
Have you learned your standard library? In particular, go look in that <tr1/functional> header file I suggested. You will find std::tr1::function - otherwise known as boost::function.

So no, nobody has suggested you use boost. Rather we have suggested that you use an element of the C++ standard library.

If someone had suggested something like boost::phoenix, I probably would have agreed with yacwroy, but for something as basic as boost::function, which has already been added to the C++ standard library, the anti-boost sentiment is ridiculous.

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Well, I might've technically said "boost::function", but that could just have easily been std::tr1::function. I think that was point that swiftcoder was making.

I also don't see the problem with recommending boost::function (or std::tr1::function) over a simple function pointer. Would you recommend someone use a simple char * until they actually "need" the functionality of std::string?

In general, I would always go the other way around: always prefer the SC++L/boost variant over whatever "raw" equivalent may exist. There's generally no (or so small as to be negligable) overhead, and the benefit in terms of flexibility and robustness are obvious.

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Much as I love boost, I wouldn't jump to it first here. It is pretty trivial to move from function pointers to boost should the need arise later. The function pointer is the simplest way, and it works.

Boost would be the best solution if the OP wanted to bind member function pointers, because boost::function and boost::bind are better options than hacking your own equivalents.

In the absence of such a requirement, YAGNI says use a function pointer. But for your own sanity use a typedef when working with function pointers [smile].

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Quote:
 Original post by CodekaI also don't see the problem with recommending boost::function (or std::tr1::function) over a simple function pointer. Would you recommend someone use a simple char * until they actually "need" the functionality of std::string?

That is completely different. Character pointers are dangerous because it is easy to make mistakes when allocating and manipulating them.

Function pointers are relatively hard to mess up in comparison, unless you start trying to cast them.

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Quote:
 Original post by swiftcoderThat is exactly my point - yacwroy is suggesting that everyone should know how to implement std::tr1::function before they use it, but the same does not hold for other elements of the standard library.

Aah, I see! At the time, it seemed straightforward that function pointers, as a core part of C++, be understood before using boost::function. I guess it would also be straightforward to use boost::function over function pointers if it was introduced first; just like std::string over char* as someone pointed out. Unfortunately, C++ is usually taught from the ground-up and function pointers, char* and typename* are encountered before std::tr1::function<>, std::string and auto<>...

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Personally I don't think function pointers are the best solution. If I want typesafety then I use boost::function (or equivalent), if I want utter simplicity then I use a template parameter...

template<typename OnFinishFunction>void CSystem::PlayMovie(const char * filename, OnFinishFunction finish){	load_movie(filename).play();	finish();}

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Quote:
Original post by swiftcoder
Every programmer who uses std::map should know how to implement a balanced red-black tree too - but you don't see anyone recommending they learn that first, do you?
Quote:
 COME ON! I've used std::map and I don't know what a red-black tree is.
That is exactly my point -

yacwroy is suggesting that everyone should know how to implement std::tr1::function before they use it

No I am not.
If you read, I say they should know how to use function pointers. This does in no way imply they should know how to implement a function pointer wrapper class.
Using function pointers is only 1: putting a function's address into a variable, and 2: calling said function from a variable.

Quote:
Original post by swiftcoder
The bigger issue I was hinting at, which you seem to have missed, is that nobody in this thread actually suggested Boost - let alone that you should rewrite your code to use boost::phoenix.
Quote:
Have you learned your standard library? In particular, go look in that <tr1/functional> header file I suggested. You will find std::tr1::function - otherwise known as boost::function. So no, nobody has suggested you use boost. Rather we have suggested that you use an element of the C++ standard library.

1. When a person says use boost::, they have suggested boost::. Even if it's in std::tr1, they said boost. And nobody here mentioned std::tr1 till you did.
2. std::tr1:: is not std::. It's not part of the standard library yet. It's just a set of candidates that may be added to std:: at some point in the future.
3. Unlikely as it seems, for all you know the std::tr1::function may undergo a syntactic change. Raw function pointers will not. boost:: may even be more concrete than std::tr1::.
Quote:
 Original post by wikipediaTR1 is not a standard itself, but rather a draft document. However, most of its proposals are likely to become part of the next official standard.

Quote:
 If someone had suggested something like boost::phoenix, I probably would have agreed with yacwroy, but for something as basic as boost::function, which has already been added (me: has not) to the C++ standard library, the anti-boost sentiment is ridiculous.

I think it's pretty unfair to call my comments anti-boost. If I say hammers are useful but you shouldn't go out and buy a hammer just to mash your potatoes or push in your doorstop, It's not anti-hammer sentiment.

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text:
# Hydrogenation at atmospheric pressure in amateur environment

I was planning on doing some small scale hydrogenation practicals at atmospheric pressure (probably from Vogel) and ran into a couple of questions. I will be using the "balloon method" (described in Procter's Advanced Practical Organic Chemistry book) as I consider it an easier technique for small scale reactions than constructing a Brown hydrogenation apparatus. Note that I'm working in an amateur environment (i.e. my home lab which does not have a fumehood). Now for the questions:

• What rule of thumb can be used to determine the amount of catalyst (in these cases $\ce{Pd/C}$) needed per mole of hydrogen used (I suppose these two variables are depending on each other)?
• There are different types of $\ce{Pd/C}$ out there: 3%, 5% or 10% $\ce{Pd}$ by weight, with or without a variable amount of added $\ce{Pb}$, different solvents (mostly I see is water) and also there are different bases available, not just palladium on carbon. I understand that $\ce{Pb}$ is added to poison the catalyst such as with Lindlar catalyst, but if total reduction is required then why would this be necessary? Also how would I decide between 3%, 5% or 10% $\ce{Pd}$ by weight?
• What is an effective method for generating the hydrogen to fill the balloon with? I suppose that normally a pressurized hydrogen tank would be used for this, but I find this overkill for the reaction I'm planning. Furthermore, the use of pressurized hydrogen tanks is not quite without danger and I'm not trained to handle them safely.
• Why would it be required to flush the reaction mixture with an inert gas after the hydrogenation has completed? I understand that this is necessary because the dissolved hydrogen gas can ignite and possibly explode when, while filtering the catalyst, the catalyst spontaneously ignites (e.g. when the catalyst is not suspended enough and direct contact with the atmosphere is possible). However, why is an inert gas advised? What is wrong with ordinary air?
• What is the function of Celite when filtering the catalyst?
• How many times can the $\ce{Pd/C}$ catalyst be reused? How would you spot whether or not your catalyst has become too poisoned to be successfully used in hydrogenation?
• The answer to some (but not all!) of your questions are probably in this video. It's a pretty cool demo of "home lab" hydrogenation. youtube.com/watch?v=oqdDWA9-DSY – Curt F. Mar 4 '15 at 19:13

As far as the catalyst is concerned, 3-5% Pd/C is fine.

What is an effective method for generating the hydrogen to fill the balloon with? I suppose that normally a pressurized hydrogen tank would be used for this, but I find this overkill for the reaction I'm planning. Furthermore, the use of pressurized hydrogen tanks is not quite without danger and I'm not trained to handle them safely.

In the lab, I only used pressurized tanks. While commercial hydrogen generators are available - they are mostly used to generate hydrogen gas as a carrier gas for GC/MS - these things cost a fortune and really would be overkill.

Actually, pressurized tanks are pretty safe if you follow some rules:

• Obviously, you can't attach the pressure regulator and operate the whole thing unless the steel cap over the main valve is removed. Don't start anything unless the tank is secured to the lab bench or the wall with a clamp, a chain or another sturdy contraption that prevents the tank from falling over! You want hydrogenation, not a rocket ;)

• Get familiar with the pressure regulator.

• When you're done, remove the regulator again and put the cap over the main valve. Keep the regulator at a dry and clean place.
• No grease on the threads!

When operated with a bit of common sense, a small pressurized tank is the most convenient option.

What is the function of Celite when filtering the catalyst?

When you filter off the catalyst, you'll typically use a suction filter with a base of sintered glass (fritted glass). Palladium on charcoal is a very fine powder that will clog the fritted glass. A pad of Celite in the suction will prevent this. Celite is cheap, suction filters are not!

• Thanks for your answer! Could you perhaps also address the other points? I cannot really accept it as an answer to the question if not the entire question is addressed. – Jori Mar 6 '15 at 12:45

Make sure you do not have any flames, anything which makes sparks or other sources of ignition near you when you do hydrogenation.

I have done plenty of hydrogenations at atmospheric preassure, I tend to use a gas burrete to follow the reaction. It is possible to see the change of rate when you consume all of the vinyl groups and then start to react a trisubsistuted alkene.

I would suggest that you consider using the nickel cataylst which is formed from nickel chloride and sodium borohydride, I have found it is a cheap and nice cataylst. It also is less pyrophoric than many other cataylsts when it has been exposed to hydrogen and is then exposed to air.

I have found that the easy way to do it is to take a 50 ml burette and turn it upside down, stuff a bung in it with a hole connected to a rubber tube which goes to a separation funnel. Put copper sulfate solution in the funnel. The blue colour makes it easy to read it more quickly and stops things growing in the water. The other end of the burette needs to be connected to the reaction flask.

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text:
Coordinate superposition with the Kabsch algorithm.

fit.xyz(fixed, mobile,
fixed.inds  = NULL,
mobile.inds = NULL,
verbose=FALSE,
prefix= "", pdbext = "",
outpath = "fitlsq", full.pdbs=FALSE,
ncore = 1, nseg.scale = 1, ...)

rot.lsq(xx, yy,
xfit = rep(TRUE, length(xx)), yfit = xfit,
verbose = FALSE)

fixed numeric vector of xyz coordinates. numeric vector, numeric matrix, or an object with an xyz component containing one or more coordinate sets. a vector of indices that selects the elements of fixed upon which fitting should be based. a vector of indices that selects the elements of mobile upon which fitting should be based. logical, if TRUE “full” coordinate files (i.e. all atoms) are written to the location specified by outpath. prefix to mobileid to locate “full” input PDB files. Only required if full.pdbs is TRUE. the file name extension of the input PDB files. character string specifing the output directory when full.pdbs is TRUE. numeric vector corresponding to the moving ‘subject’ coordinate set. numeric vector corresponding to the fixed ‘target’ coordinate set. logical vector with the same length as xx, with TRUE elements corresponding to the subset of positions upon which fitting is to be performed. logical vector with the same length as yy, with TRUE elements corresponding to the subset of positions upon which fitting is to be performed. logical, if TRUE more details are printed. other parameters for read.pdb. number of CPU cores used to do the calculation. ncore>1 requires package ‘parallel’ installed. split input data into specified number of segments prior to running multiple core calculation. ## Details The function fit.xyz is a wrapper for the function rot.lsq, which performs the actual coordinate superposition. The function rot.lsq is an implementation of the Kabsch algorithm (Kabsch, 1978) and evaluates the optimal rotation matrix to minimize the RMSD between two structures. Since the Kabsch algorithm assumes that the number of points are the same in the two input structures, care should be taken to ensure that consistent atom sets are selected with fixed.inds and mobile.inds. Optionally, “full” PDB file superposition and output can be accomplished by setting full.pdbs=TRUE. In that case, the input (mobile) passed to fit.xyz should be a list object obtained with the function read.fasta.pdb, since the components id, resno and xyz are required to establish correspondences. See the examples below. In dealing with large vector and matrix, running on multiple cores, especially when ncore>>1, may ask for a large portion of system memory. To avoid the overuse of memory, input data is first split into segments (for xyz matrix, the splitting is along the row). The number of data segments is equal to nseg.scale*nseg.base, where nseg.base  is an integer determined by the dimension of the data. ## Value Returns moved coordinates. ## References Grant, B.J. et al. (2006) Bioinformatics 22, 2695--2696. Kabsch Acta Cryst (1978) A34, 827--828. ## Author Barry Grant with rot.lsq contributions from Leo Caves ## See also rmsd, read.pdb, read.fasta.pdb, read.dcd ## Examples # \donttest{ # PDB server connection required - testing excluded ##--- Read an alignment & Fit aligned structures aln <- read.fasta(system.file("examples/kif1a.fa",package="bio3d")) pdbs <- read.fasta.pdb(aln) #> pdb/seq: 1 name: http://www.rcsb.org/pdb/files/1bg2.pdb #> pdb/seq: 2 name: http://www.rcsb.org/pdb/files/1i6i.pdb #> PDB has ALT records, taking A only, rm.alt=TRUE #> pdb/seq: 3 name: http://www.rcsb.org/pdb/files/1i5s.pdb #> PDB has ALT records, taking A only, rm.alt=TRUE #> pdb/seq: 4 name: http://www.rcsb.org/pdb/files/2ncd.pdb gaps <- gap.inspect(pdbsxyz)

xyz <- fit.xyz( fixed  = pdbs$xyz[1,], mobile = pdbs$xyz,
fixed.inds  = gaps$f.inds, mobile.inds = gaps$f.inds )

#rmsd( xyz[, gaps$f.inds] ) #rmsd( pdbs$xyz[, gaps$f.inds] ) ##-- Superpose again this time outputing PDBs xyz <- fit.xyz( fixed = pdbs$xyz[1,],
mobile = pdbs,
fixed.inds  = gaps$f.inds, mobile.inds = gaps$f.inds,
outpath = "rough_fit",
full.pdbs = TRUE)
#>    PDB has ALT records, taking A only, rm.alt=TRUE
#>    PDB has ALT records, taking A only, rm.alt=TRUE
##--- Fit two PDBs
#>   Note: Accessing on-line PDB fileA.ind <- atom.select(A, resno=c(256:269), elety='CA')

xyz <- fit.xyz(fixed=A$xyz, mobile=B$xyz,
fixed.inds=A.ind$xyz, mobile.inds=B.ind$xyz)


text:
# Solved papers for AMU Medical AMU Solved Paper-1999

### done AMU Solved Paper-1999

• question_answer1) Four particles of masses m, 2m, 3m and 4m are arranged at the corners of a parallelogram with each side equal to a and one of the angle between two adjacent sides as$60{}^\circ$. The parallelogram lies in the $x-y$ plane with mass m at the origin and 4m on the $x-$axis. The centre of mass of the arrangement will be located at

A) $\left( \frac{\sqrt{3}}{2}a,0.95a \right)$

B) $\left( 0.95a,\frac{\sqrt{3}}{4}a \right)$

C) $\left( \frac{3a}{4},\frac{a}{2} \right)$

D) $\left( \frac{a}{2},\frac{3a}{4} \right)$

• question_answer2) A 20 kg block is initially at rest on a rough horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. The coefficient of static friction is

A) 0.38

B) 0.44

C) 0.52

D) 0.60

• question_answer3) The total kinetic energy of a rolling sphere having translational velocity V is

A) $\frac{7}{10}M{{V}^{2}}$

B) $\frac{1}{2}M{{V}^{2}}$

C) $\frac{2}{5}M{{V}^{2}}$

D) $\frac{10}{7}M{{V}^{2}}$

• question_answer4) An elastic string has length$\beta$when subjected to 5 N tension. Its length is a when tension 4 N. When subjected to a tension of 9 N, its length will become

A) $9(\beta -\alpha )$

B) $5\alpha -4\beta$

C) $5\beta -4\alpha$

D) $\beta -\alpha$

• question_answer5) During a journey from earth to moon and back, the greatest energy required from the rocket of the space ship is to overcome

A) the moons gravity at lunar landing

B) the moons gravity at lunar take off

C) the earths gravity at re-entry into earths atmosphere

D) the earths gravity at take off

• question_answer6) A ball is rolled off the edge of a horizontal table at a speed of 4 m/second. It hits the ground after 0.4 second. Which statement given below is not true?

A) it hits the ground at a horizontal distance 1.6 m from the edge of the table

B) the speed with which it hits the ground is 0.4m/second

C) height of the table is 0.8 m

D) it hits the ground at an angle of$45{}^\circ$to the horizontal

• question_answer7) A body of mass M kg initially at rest explodes into three fragments having masses in the ratio$3:1:1$. The two equal mass fragments fly off at right angles to each other with equal speed of 60 m/s. The speed of the heavier fragment is

A) $30\sqrt{2}\,m/s$

B) $10\sqrt{2}\,m/s$

C) $20\sqrt{2}\,m/s$

D) $20\,m/s$

• question_answer8) Three masses are connected (as Shown) on a horizontal frictionless surface and pulled by a force of 60 N. The tensions${{T}_{1}}$and${{T}_{2}}$are in the ratio

A) $1:1$

B) $1:5$

C) $1:4$

D) $4:5$

• question_answer9) A body is moved along a straight line by a machine which delivers constant power. The distance moved by the body in time$t$is proportional to

A) $t$

B) ${{t}^{1/2}}$

C) ${{t}^{5/2}}$

D) ${{t}^{3/2}}$

• question_answer10) If the speed of light [c], acceleration due to gravity [g] and pressure [P] are taken as the fundamental quantities, then the dimension of gravitational constant is

A) ${{c}^{2}}{{g}^{0}}{{p}^{-2}}$

B) ${{c}^{0}}{{g}^{2}}{{p}^{-1}}$

C) $c{{g}^{3}}{{p}^{-2}}$

D) $c{{g}^{0}}{{p}^{-1}}$

• question_answer11) If the kinetic energy of one mole of an ideal gas is given as$E=\frac{3}{2}RT$ (where 7? is the universal gas constant and T is the absolute temperature of the gas), the molar specific heat at constant pressure will be given as

A) $2.5\text{ }R$

B) $1.5\text{ }R$

C) $0.5\text{ }R$

D) $0.1\text{ }R$

• question_answer12) Which one of the following statement is true?

A) for monoatomic gases $\gamma =1.40$

B) for diatomic gases ${{C}_{p}}-{{C}_{V}}=2\text{ }cal$

C) for polyatomic gases $\gamma =1.67$

D) for all the gases ${{C}_{p}}=4R$

• question_answer13) A Carnot engine working between 300 K and 600 K has a work output of 800 joules per cycle. The amount of heat energy supplied from the source to the engine in each cycle is

A) 6400 joule

B) 1600 joule

C) 3200 joule

D) 800 joule

• question_answer14) Oxygen and hydrogen gases are at the same temperature and pressure. The oxygen molecule has 16 times the mass of hydrogen molecule. The ratio of the root mean square velocity of oxygen molecule to that of hydrogen molecule will be

A) 16

B) 4

C) 2

D) 1/4

• question_answer15) A thin metal disc of radius r floats on water surface and bends the surface downwards along the perimeter making an angle$\theta$with verticle edge of the disc. If the disc displaces a weight of water W and surface tension of water is T, then the weight of metal disc is

A) $2\pi rT+W$

B) $2\pi rT\cos \theta -W$

C) $2\pi rT\cos \theta +W$

D) $W-2\pi rT\cos \theta$

• question_answer16) A block of mass is suspended from a spring balance. When the block is in air the balance reads 120 N. When it is immersed in water the reading changes to 80 N. The relative density of the material of the block is

A) 6

B) $\frac{6}{2}$

C) $\frac{6}{3}$

D) $\frac{6}{4}$

• question_answer17) A 10 cm long wire is placed horizontally on the surface of water and is gently pulled up with a force of $2\times {{10}^{-2}}N$to keep the wire in equilibrium. The surface tension, in$N{{m}^{-1}}$of water is

A) 0.1

B) 0.2

C) 0.001

D) 0.002

• question_answer18) Radius of gyration of uniform thin rod of length about an axis passing normally through its centre of mass is

A) $\frac{L}{\sqrt{12}}$

B) $\frac{L}{12}$

C) $\sqrt{12}L$

D) $12L$

• question_answer19) An artificial satellite is placed into a circular orbit around earth at such a height that it always remains about a definite place on the surface of earth. Its height from the surface of earth is

A) 6400 km

B) 4800 km

C) 32000km

D) 36000km

• question_answer20) A pendulum bob of mass 50 gm is suspended from the ceiling of an elevator. The tension in the string if the elevator goes up with uniform velocity is approximately

A) 0.30 N

B) 0.40 N

C) 0.42 N

D) 0.50 N

• question_answer21) An infinite ladder network is arranged with resistances$R$and$2R$as shown. The effective resistance between terminals A and B is

A) $\infty$

B) $R$

C) $2R$

D) $3R$

• question_answer22) A wire of resistance$1\,\Omega$is stretched to double its length. The resistance of the wire will become

A) $1\,\Omega$

B) $\frac{1}{4}\,\Omega$

C) $2\,\Omega$

D) $4\,\Omega$

• question_answer23) The electric field in a region is radially outward with magnitude$E=Ar$. The charge contained in a sphere of radius${{r}_{0}}$centered at the origin is

A) $\frac{1}{4\pi {{\varepsilon }_{0}}}Ar_{0}^{3}$

B) $4\pi {{\varepsilon }_{0}}\,Ar_{0}^{3}$

C) $\frac{4\pi {{\varepsilon }_{0}}A}{r_{0}^{3}}$

D) $\frac{1}{4\pi {{\varepsilon }_{0}}}.\frac{A}{r_{0}^{3}}$

• question_answer24) If a slab of insulating material$4\times {{10}^{-3}}$m thick is introduced between the plates of a parallel plate capacitor, the separation between plates has to be increased by$3.5\times {{10}^{-3}}$m to restore the capacity to original value. The dielectric constant of the material will be

A) 6

B) 8

C) 10

D) 12

• question_answer25) What is the potential energy of the equal positive point charges of$1\,\mu C$each held 1 m apart in air?

A) $9\times {{10}^{-3}}J$

B) $9\times {{10}^{-3}}eV$

C) $1J$

D) zero

• question_answer26) A whistle of frequency 500 Hz tied to the end of a string of length 1.2 m revolves at 400 revolutions per minute. If the velocity of sound is 340 m/sec, a listener standing some distance away in the plane of rotation of the whistle hears the frequencies in the range

A) 436 to 586 Hz

B) 426 to 574 Hz

C) 436 to 574 Hz

D) 426 to 586 Hz

• question_answer27) A stationary wave is expressed as $y=4\sin \left( \frac{\pi x}{3} \right)\cos (40\pi t)$ where$x$ and y are measured in cm and time t in second. The separation between consecutive nodes is

A) 1.5 cm

B) 6 cm

C) 12 cm

D) 3 cm

• question_answer28) A$1.00\times {{10}^{-20}}kg$particle is vibrating with simple harmonic motion with a period of$1.00\times {{10}^{-5}}$s and a maximum speed of$1.00\times {{10}^{3}}m/s$. The maximum displacement of the particle is

A) 1.59mm

B) 1.00m

C) 10 m

D) none of the above

• question_answer29) A Simple harmonic wave is represented by the relation$y=a\sin 2\pi \left( pt-\frac{x}{\lambda } \right)$where a and y are measured in cm and time$t$in seconds. The maximum particle velocity is five times the wave velocity. The wavelength of the wave is

A) $\frac{2\pi a}{\sqrt{5}}cm$

B) $\frac{2\pi a}{5}cm$

C) $\frac{\pi a}{5}cm$

D) $2\sqrt{5}\pi a\,cm$

• question_answer30) A slab of thickness${{d}_{1}}$and coefficient of thermal conductivity${{K}_{1}}$. is placed in contact with another slab of thickness${{d}_{2}}$and coefficient of thermal conductivity${{K}_{2}}$. In steady state, the conductivity of composite slab will be

A) $\frac{{{d}_{1}}+{{d}_{2}}}{{{K}_{1}}+{{K}_{2}}}$

B) $\frac{{{K}_{1}}{{K}_{2}}}{{{K}_{1}}{{d}_{2}}+{{K}_{2}}{{d}_{1}}}$

C) $\frac{{{K}_{1}}{{d}_{1}}+{{K}_{2}}{{d}_{2}}}{{{d}_{1}}+{{d}_{2}}}$

D) $\frac{{{d}_{1}}+{{d}_{2}}}{\left( \frac{{{d}_{1}}}{{{K}_{1}}}+\frac{{{d}_{2}}}{{{K}_{2}}} \right)}$

• question_answer31) What is the frequency of radio waves corresponding to 10 m wavelength?

A) $3\times {{10}^{9}}Hz$

B) $3.3\times {{10}^{-8}}Hz$

C) $3\times {{10}^{7}}Hz$

D) $3.4\times {{10}^{-7}}Hz$

• question_answer32) A monochromatic light beam of wavelength 2537 A is falling normally on a metal plate. If the maximum velocity of emitted photoelectron is $1.6\times {{10}^{5}}m/sec$ and a constant magnetic field of strength ${{10}^{-4}}$ $weber/{{m}^{2}}$is applied parallel to metal surface, the radius of the largest circular path of photoelectrons is

A) 0.61 m

B) 0.61 cm

C) $6.1\times {{10}^{-4}}m$

D) $6.1\times {{10}^{-5}}m$

• question_answer33) Suppose electromagnetic waves having speed $2.5\times {{10}^{8}}$m/sec are travelling in a medium of relative permeability 0.8. The relative permitivity is

A) 1.0

B) 1.8

C) 2.5

D) none of these

• question_answer34) The effective value of A.C. in a circuit is 10 A. The peak value of current is

A) 5 A

B) 0.707 A

C) 10 A

D) 14.14 A

• question_answer35) An LC circuit contains a 40 mH inductor and a $25\,\mu F$capacitor. The resistance of the circuit is negligible. The energy stored in the circuit is completely magnetic at times (in milliseconds). The time is measured from the instant the circuit is closed

A) 0, 3.14, 6.28

B) 0, 1.57, 4.71

C) 1.57, 4.71, 7.85

D) none of the above

• question_answer36) A cyclotron is accelerating proton, where the applied magnetic field is 2 T, the potential gap is 100 kV then how much turn the proton has to move between the dees to acquire a kinetic energy of 20 MeV

A) 100

B) 150

C) 200

D) 300

• question_answer37) The magnetic induction in the region between the pole faces of an electromagnet is 0.7 weber/${{m}^{2}}$. The induced e.m.f. in a straight conductor 10 cm long, perpendicular to B and moving perpendicular both to magnetic induction and its own length with a velocity 2 m/sec is

A) 0.08 V

B) 0.14V

C) 0.35 V

D) 0.07 V

• question_answer38) A circular coil of diameter 7cm has 24 turns of wire carrying current of 0.75A. The magnetic moment of the coil is

A) $6.9\times {{10}^{-2}}A{{m}^{2}}$

B) $2.3\times {{10}^{-2}}A{{m}^{2}}$

C) ${{10}^{-2}}A{{m}^{2}}$

D) ${{10}^{-3}}A{{m}^{2}}$

• question_answer39) A certain current passing through a copper voltameter deposits 0.002 kg of copper on cathode plate in 100 minutes. If there are${{10}^{25}}$ copper atoms in 1kg of copper, the electric charge delivered to cathode by copper ions$(C{{u}^{2+}})$per second will be

A) 1.06 C

B) 2.13 C

C) 0.53 C

D) 0.71 C

• question_answer40) A current$i$passes through a wire of length$l$, radius of cross-section r, and resistivity $\rho$. The rate of heat generation is

A) $\frac{{{i}^{2}}l\rho }{\pi {{r}^{2}}}$

B) ${{i}^{2}}{{\left( \frac{l\rho }{\pi {{r}^{2}}} \right)}^{2}}$

C) ${{i}^{2}}l\rho /r$

D) $il\rho /r$

• question_answer41) The star Sirius is emitting radiation with the radiant intensity (energy emitted per unit area per second) of$1.2\times {{10}^{7}}W/{{m}^{2}}$the colour of this star will be

A) blue

B) yellow

C) green

D) red

• question_answer42) Transistors provide good power amplification when they are used in

A) common emitter configuration

B) common base configuration

C) common collector configuration

D) none of the above

• question_answer43) The following combination of gates is equivalent to which of the following gate

A) XOR

B) OR

C) NAND

D) none of the above

• question_answer44) When a hydrogen atom is raised from the ground state to an excited state

A) both kinetic energy and potential energy increase

B) both kinetic energy and potential energy decrease

C) potential energy increases, kinetic energy decreases

D) potential energy decreases, kinetic energy increases

• question_answer45) A freshly prepared radioactive substance of half-life half an hour emits radiation of intensity thirty two times the permissible safe limit. The minimum time after which it would be safe to work with the substance is

A) 3 hours

B) 6 hours

C) 2 hours

D) 8 hours

• question_answer46) Consider the following two statements [A] Energy spectrum of a particles emitted in radioactive decay is discrete [B] Energy spectrum of P particles emitted in radioactive decay is continuous

A) only A is correct

B) only B is correct

C) A is correct but B is wrong

D) both A and B are correct

• question_answer47) An oil drop having charge 2e is kept stationary between two parallel horizontal plates 2.0 cm apart when a potential difference of 12000 volts is applied between them. If the density of oil is$900\text{ }kg/{{m}^{3}}$, the radius of the drop will be

A) $2.0\times {{10}^{-6}}m$

B) $1.7\times {{10}^{-6}}m$

C) $1.4\times {{10}^{-6}}m$

D) $1.1\times {{10}^{-6}}m$

• question_answer48) Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 A falls on the surface, the velocity of the fastest electron ejected from the surface will be

A) $8.4\times {{10}^{5}}$m/second

B) $7.4\times {{10}^{5}}$m/second

C) $6.4\times {{10}^{5}}$m/second

D) $8.4\times {{10}^{6}}$m/second

• question_answer49) A convex lens is used to form real image of an object on a screen. It is observed that even when the positions of the object and the screen are fixed there are two positions of the lens to form real images. If the heights of the images are 4 cm and 9cm respectively, the height of the objective is;

A) 2.25 cm

B) 6.00 cm

C) 6.50 cm

D) 36.00 cm

• question_answer50) A compound microscope is 20 cm long and the power of its eye-piece is 20 D. If the objective is bi-convex (radius of curvature of either surface 2 cm) and made of a material of = 1.5, the magnifying power of the microscope is

A) 54

B) 60

C) 13.5

D) 41.5

• question_answer51) The internal energy of a system is the sum of

A) vibrational energy and electronic energy

B) vibrational energy and rotational energy

C) vibrational energy, rotational energy, electronic energy and translational energy

D) rotational energy and electronic energy

• question_answer52) The maximum number of permissible rotational orientations of the Is electron of lithium atom in ground state is

A) 1

B) 2

C) 3

D) 4

• question_answer53) Which of the following is the correct bond order for$N_{2}^{2-}$ion?

A) 2.5

B) 2.0

C) 3.0

D) 1.5

• question_answer54) Of the following iso-electronic ions, the one which has the lowest ionization potential is

A) $N{{a}^{+}}$

B) $M{{g}^{++}}$

C) ${{F}^{-}}$

D) ${{O}^{--}}$

• question_answer55) What is the effect of more electronegative atom on the strength of ionic bond?

A) decreases

B) increases

C) remains same

D) any one of these

• question_answer56) If we consider the ammonia molecule to be $s{{p}^{3}}$ hybridized, the lone pair will occupy

A) an s-orbital

B) a p-orbital

C) a$s{{p}^{2}}-$hybridized orbital

D) a$s{{p}^{3}}-$hybridized orbital

• question_answer57) Rate constants of some reactions are given below. Predict which one indicates third order of reaction?

A) $k=8.7\times {{10}^{-3}}mo{{l}^{-1}}L{{s}^{-1}}$

B) $k=6.5\times {{10}^{-4}}mol{{L}^{-1}}{{s}^{-1}}$

C) $k=5.3\times {{10}^{-5}}{{s}^{-1}}$

D) $k=2.52\times {{10}^{-32}}mo{{l}^{-2}}{{L}^{2}}{{s}^{-1}}$

• question_answer58) A zinc rod is placed in 0.095 M solution of zinc sulphate at 298 K, the potential of the electrode at this temperature is[$E_{Zn}^{o}=-0.76$volts]

A) $-0.79$volts

B) $-0.69$volts

C) $-0.59$volts

D) $-0.49$volts

• question_answer59) Which of the following hydrogen bonds are strongest in vapour phase?

A) $HF---HF$

B) $HF---HCl$

C) $HCl---HCl$

D) $HF---HI$

• question_answer60) A primary alcohol,${{C}_{3}}{{H}_{8}}O$ on heating with sulphuric acid undergo dehydration to give an alkene, B.B when reacted with$HCl$gave C, which on treatment with aqueous KOH gives compound $D,{{C}_{3}}{{H}_{8}}O.A$and D are

A) functional isomers

B) position isomers

C) chain isomers

D) stereo isomers

• question_answer61) In the series of bivalent hydrides of sixteenth group elements

A) volatility increases from${{H}_{2}}O$to${{H}_{2}}S$and then decreases

B) volatility increases from${{H}_{2}}O$to ${{H}_{2}}Se$

C) volatility decreases from${{H}_{2}}O$to${{H}_{2}}Se$

D) none of the above

• question_answer62) Of the aliphatic compound carrying the following functional groups the one which cannot exhibit position isomerism is

A) carbon-carbon double bond

B) carbon-carbon triple bond

C) keto group

D) carboxylic acid group

• question_answer63) When ethanol is subjected to dehydration in presence of${{H}_{2}}S{{O}_{4}},$the intermediate formed is a

A) carbonium ion

B) carbanion

D) carbine

• question_answer64) Which of the following can act as an acid and as a base?

A) $HCO_{3}^{-}$

B) ${{H}_{2}}PO_{4}^{-}$

C) Both (a) and (b)

D) None of these

• question_answer65) $200\text{ }c{{m}^{3}}$of an aqueous solution of a protein contains 1.26 g. of protein. The O.P. of such a solution at 300 K is found to be$2.57\times {{10}^{-3}}$atm. Molar mass of protein is

A) $60287\text{ }g.mo{{l}^{-1}}$

B) $30242.\text{ }g.mo{{l}^{-1}}$

C) $40404\text{ }g.\text{ }mo{{l}^{-1}}$

D) $50404\text{ }g.\text{ }mo{{l}^{-1}}$

• question_answer66) What is the magnetic moment for$M{{n}^{2+}}$ion in low spin state?

A) 5.90 BM

B) 8.90 BM

C) 2.8 BM

D) 1.73 BM

• question_answer67) On mole of a gas absorbs 300 J of heat at constant volume and its temperature is raised from 30 to$35{}^\circ C$. The value of$\Delta E$is

A) 300 joules

B) 0.1 joules

C) 150 joules

D) 200 joules

• question_answer68) In which of the following conditions a chemical reaction can not occur?

A) $\Delta H$ and$\Delta S$increase and$T\Delta S>\Delta H$

B) $\Delta H$and$\Delta S$decrease and $\Delta H>T\Delta S$

C) $\Delta H$increases and$\Delta S$increases

D) $\Delta H$decreases and$\Delta S$increases

• question_answer69) If the melting point of ice is$0{}^\circ C$and latent heat of fusion is$5.46\text{ }kJ\text{ }mo{{l}^{-1}}$, the entropy change for the conversion of 18 g of ice to water at one atmosphere is

A) $5.46\text{ }J{{K}^{-1}}$

B) $20\text{ }J{{K}^{-1}}$

C) $50\text{ }J{{K}^{-1}}$

D) $\text{360 }J{{K}^{-1}}$

• question_answer70) Calculate the uncertainty in the velocity of a cricket ball of 100 g if the uncertainty in its position is$1.65\text{ }\overset{o}{\mathop{\text{A}}}\,$.

A) $1.657\pi \times {{10}^{-43}}m/s$

B) $\frac{6.6}{\pi }\times {{10}^{-45}}m/s$

C) $\frac{{{10}^{-23}}}{\pi }m/s$

D) $\frac{{{10}^{-26}}}{\pi }m/s$

• question_answer71) The correct order of basicity of amines in water is

A) $C{{H}_{3}}N{{H}_{2}}>{{(C{{H}_{3}})}_{2}}NH>{{(C{{H}_{3}})}_{3}}N$

B) ${{(C{{H}_{3}})}_{3}}N>{{(C{{H}_{3}})}_{2}}NH>C{{H}_{3}}N{{H}_{2}}$

C) ${{(C{{H}_{3}})}_{2}}NH>{{(C{{H}_{3}})}_{3}}N>C{{H}_{3}}N{{H}_{2}}$

D) none of the above

• question_answer72) Solubility of lead chloride is K. Then the number of moles of $C{{l}^{-}}$ionsin 1000 ml of saturated lead chloride solution will be

A) ${{\left( \frac{K}{4} \right)}^{1/3}}$

B) ${{(2K)}^{1/3}}$

C) ${{K}^{1/2}}$

D) $\frac{K}{2}$

• question_answer73) The compounds that will undergo Cannizzaro reaction are 1. $C{{H}_{3}}CHO$ 2. ${{(C{{H}_{3}})}_{3}}CCHO$ 3. $PhCHO$ 4. $C{{H}_{3}}COC{{H}_{3}}$

A) 1 and 2

B) 1 and 3

C) 2 and 3

D) 2 and 4

• question_answer74) The freezing point of a 0.01 m aqueous glucose solution at 1 atmosphere is$-0.18{}^\circ C$. To it, an addition of equal volume of 0.002 m glucose solution will produce a solution with freezing point of nearly

A) $-0.036{}^\circ C$

B) $-0.108{}^\circ C$

C) $-0.216{}^\circ C$

D) $-0.422{}^\circ C$

• question_answer75) 60 J of heat flows out from 600 g. of${{H}_{2}}O$at $30{}^\circ C$into the surroundings at$25{}^\circ C$. The total entropy change in the universe due to this process is

A) $0.1\text{ }J{{K}^{-1}}$

B) $0.5\text{ }J{{K}^{-1}}$

C) $0.9J{{K}^{-1}}$

D) $1.0\text{ }J{{K}^{-1}}$

• question_answer76) Which of the following is a better electron pair donor?

A) $P{{(C{{H}_{3}})}_{3}}$

B) $P{{H}_{3}}$

C) $N{{(C{{H}_{3}})}_{3}}$

D) $N{{H}_{3}}$

• question_answer77) The compounds that will give an isomer of 2,2- dimethylpropane on catalytic hydrogenation are (1) $C{{H}_{3}}CH=\underset{\begin{smallmatrix} | \\ C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}$ (2) $C{{H}_{3}}CH=CHC{{H}_{3}}$ (3) $C{{H}_{3}}CH=CHC{{H}_{2}}C{{H}_{3}}$ (4) $C{{H}_{3}}\underset{\begin{smallmatrix} | \\ C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,=\underset{\begin{smallmatrix} | \\ C{{H}_{3}} \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{3}}$

A) 1 and 4

B) 2 and 4

C) 1 and 3

D) 1 and 2

• question_answer78) What is the correct mode of hybridization of the central atom in the following compounds?

A) $NO_{2}^{+}$ - $s{{p}^{2}}$ $S{{F}_{4}}$ - $s{{p}^{3}}$ $PF_{6}^{-}$ - ${{d}^{2}}s{{p}^{3}}$

B) $NO_{2}^{+}$ - $s{{p}^{3}}$ $S{{F}_{4}}$ - $s{{p}^{3}}{{d}^{2}}$ $PF_{6}^{-}$ - $s{{p}^{3}}{{d}^{2}}$

C) $NO_{2}^{+}$ - $sp$ $S{{F}_{4}}$ - $s{{p}^{3}}d$ $PF_{6}^{-}$ - $s{{p}^{3}}{{d}^{2}}$

D) $NO_{2}^{+}$ - $sp$ $S{{F}_{4}}$ - $s{{p}^{2}}$ $PF_{6}^{-}$ - $s{{p}^{3}}$

• question_answer79) Which of the following statements is correct?

A) $S{{F}_{4}}$is polar and nonreactive

B) $S{{F}_{6}}$is nonpolar and very reactive

C) $S{{F}_{6}}$is a strong fluorinating agent

D) $S{{F}_{4}}$is prepared by fluorinating$SC{{l}_{2}}$with$NaF$

• question_answer80) An ionic compound$XY$has a structure of ZnS type. If the radius of${{X}^{+}}$is 22.5 pm. The ideal radius of$Y-$will be

A) 100 pm

B) 50 pm

C) 20 pm

D) 30 pm

• question_answer81) The pH of a soft drink is 3.82. The hydrogen ion concentration of the drink is (Antilog 0.18=1.5)

A) $1.96\times {{10}^{-2}}mole\text{ }li{{t}^{-1}}$

B) $1.96\times {{10}^{-3}}mole\text{ }li{{t}^{-1}}$

C) $1.5\times {{10}^{-4}}mole\text{ }li{{t}^{-1}}$

D) $1.5\times {{10}^{-3}}mole\text{ }li{{t}^{-1}}$

• question_answer82) If an amide is treated with${{P}_{2}}{{O}_{5}}$the likely product is an

A) acid

B) alkyl cyanide

C) amine

D) acid anhydride

• question_answer83) The polymer used for making contact lenses for eyes is

A) poly methyl methacrylate

B) polyethylene

C) polyethyl acrylate

D) nylon 6

• question_answer84) Silver sulphide dissolves in a solution of sodium cyanide to form the complex

A) $Na[Ag{{(CN)}_{2}}]$

B) $N{{a}_{3}}[Ag{{(CN)}_{4}}]$

C) $N{{a}_{5}}[Ag{{(CN)}_{6}}]$

D) $N{{a}_{2}}[Ag{{(CN)}_{2}}]$

• question_answer85) The compound that can be formed by aldol condensation of acetaldehyde is

A) $C{{H}_{3}}-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{2}}-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

B) $C{{H}_{3}}-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-C{{H}_{2}}-COOH$

C) $C{{H}_{3}}-C{{H}_{2}}-\underset{\begin{smallmatrix} | \\ OH \end{smallmatrix}}{\mathop{CH}}\,-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

D) $C{{H}_{3}}-\underset{\begin{smallmatrix} | \\ OH \end{smallmatrix}}{\mathop{CH}}\,-C{{H}_{2}}-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

• question_answer86) Phenol is less acidic than

A) acetylene

B) para methoxy phenol

C) ethanol

D) para nitro phenol

• question_answer87) In a${{H}_{2}}{{O}_{2}}$fuel cell, 67.2 litre of${{H}_{2}}$at STP react in 10 minutes as per following reaction- Anode ${{H}_{2}}+2O{{H}^{-}}\to 2{{H}_{2}}O+2{{e}^{-}}$ Cathode ${{O}_{2}}+2{{H}_{2}}O+2{{e}^{-}}\to 4O{{H}^{-}}$ The average current produced by the fuel cell will be

A) 5 milliampere

B) 10 milliampere

C) 482.7 ampere

D) 965.4 ampere

• question_answer88) The element of atomic number 11 is highly reactive, which of the following elements will be most likely to be reactive metal?

A) Elementwithat.no. 17

B) Element with at. no. 24

C) Element with at. no. 37

D) Element with at. no. 54

• question_answer89) What type of hybridization is involved in ${{[Fe{{(CN)}_{6}}]}^{3-}}$

A) ${{d}^{2}}s{{p}^{3}}$

B) $ds{{p}^{2}}$

C) $s{{p}^{3}}{{d}^{3}}$

D) $ds{{p}^{3}}$

• question_answer90) Molar conductivity of a solution of an electrolyte$A{{B}_{2}}$is$160\text{ }oh{{m}^{-1}}c{{m}^{2}}mo{{l}^{-1}}$. If it ionizes as$A{{B}_{2}}\to {{A}^{+2}}+2{{B}^{-1}}$. Its equivalent conductivity will be

A) $150\text{ }oh{{m}^{-1}}c{{m}^{-1}}mo{{l}^{-1}}$

B) $\text{75 }oh{{m}^{-1}}c{{m}^{-1}}mo{{l}^{-1}}$

C) $\text{80 }oh{{m}^{-1}}c{{m}^{-1}}mo{{l}^{-1}}$

D) all of the above

• question_answer91) In${{S}_{N}}2$reactions the sequence of bond breaking and bond formation is as follows

A) bond breaking is followed by formation

B) bond formation is followed by breaking

C) bond breaking and formation are simultaneous

D) bond breaking and formation take place randomly

• question_answer92) Which of the following on nuclear bromination can yield only one monobromo derivative?

A) ortho xylene

B) meta xylene

C) para xylene

D) toluene

• question_answer93) Which of the following shows highest magnetic moment?

A) ${{V}^{3+}}$

B) $C{{r}^{3+}}$

C) $M{{n}^{2+}}$

D) $F{{e}^{2+}}$

• question_answer94) Which of the following can exhibit keto-enol tautomerism?

A) $C{{H}_{3}}-\overset{\begin{smallmatrix} O \\ || \end{smallmatrix}}{\mathop{C}}\,-H$

B) $CC{{l}_{3}}-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

C) $H-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

D) ${{(C{{H}_{3}})}_{3}}C-\underset{\begin{smallmatrix} || \\ O \end{smallmatrix}}{\mathop{C}}\,-H$

• question_answer95) CP-LCN is known as acetonitrile because

A) it contains an aceto group

B) on hydrolysis it gives acetic acid

C) acetic acid is converted to it by direct reaction with HCN

D) acetyl chloride on reaction with HCN gives the compound

• question_answer96) In the following four compounds, the one which is a functional isomer of the set of other three is

A)

B)

C)

D)

• question_answer97) Diethyl ether is isomeric with

A) primary alcohol

B) secondary alcohol

C) tert. alcohol

D) all of these

• question_answer98) The same quantity of electricity was passed through salt solutions of silver (at. wt. = 107.9) and gold (at. wt. = 197). If 1.439 g of Ag and 0.876 g of Au were deposited, the oxidation state of Au in the salt is

A) zero

B) +2

C) +3

D) +1

• question_answer99) ${{H}_{2}}S$acts only as a reducing agent while$S{{O}_{2}},$can act both as a reducing and oxidizing agent because

A) S in${{H}_{2}}S$has -2 oxidation state

B) S in$S{{O}_{2}}$has oxidation state$+4$

C) hydrogen in${{H}_{2}}S$is more +ve than oxygen in$S{{O}_{2}}$

D) oxygen is more -ve in$S{{O}_{2}}$

• question_answer100) In the equilibrium ${{A}^{-}}+{{H}_{2}}O\rightleftharpoons HA+O{{H}^{-}}$ $({{K}_{a}}=1.0\times {{10}^{-5}})$ The degree of hydrolysis of 0.001 M solution of the salt is

A) ${{10}^{-3}}$

B) ${{10}^{-4}}$

C) ${{10}^{-5}}$

D) ${{10}^{-6}}$

• question_answer101) A situation where one population is benefitted while the other unaffected is referred as

A) commensalism

B) parasitism

C) amensalism

D) symphily.

• question_answer102) Which of the following is incorrect?

A) iodine is needed for thyroxine formation

B) calcium regulates the excitibility of nerve fibres ag

C) potassium plays an important role in the regulation of acid-base balance in cell

D) phosphorous helps to maintain the osmotic pressure of the body fluids.

• question_answer103) The first antibody which gets formed in response to an antigen is

A) $IgM$

B) $IgG$

C) $IgA$

D) none of these.

• question_answer104) Megakaryocytes are the

A) cells found between the spaces in the lamellae of compact bone tissues

B) cells of bone marrow which give rise to thrombocytes

C) phagocytes found in the lymph

D) another name for thrombocytes.

• question_answer105) The hepatic cells which act as phagocytes are

A) Hansens cells

B) acinar cells

C) Kupffer cells

D) none of these.

• question_answer106) Which of the following is incorrect sequence in classification?

A) amphibia-anura-frog

B) reptilia-squamata-ophidia-shake

C) aves-neognathae-passeriformes-sparrow

D) mammalia-eutheria-artiodactyla-horse.

• question_answer107) Sea lilies are

A) echinoderms

B) coelenterates

C) rotifers

D) aquatic plants.

• question_answer108) Enterogastrone secretion is induced by

A) bile

B) fatty acids.

C) $HCl$

D) pancreatic juice

• question_answer109) Binding of ATP to myosin required the cofactor

A) Mg

B) Na

C) K

D) Ca.

• question_answer110) Cumulus cells are generally found around

A) corpus luteum

B) ovulated eggs

C) ovary

D) uterus.

• question_answer111) Which of the following chambers of ruminant stomach contains the gastric juice?

A) abomasum

B) omasum

C) rumen

D) reticulum.

• question_answer112) The embryonic skeleton is formed by

A) white fibrous cartilage

B) elastic cartilage

C) hyaline cartilage

D) none of the above.

• question_answer113) Reticular tissue forms the supporting frame work of

A) bone marrow

B) lymph gland

C) spleen

D) all of these.

• question_answer114) Which of the following organisms causes the sexual disease syphilis?

A) Neisseria gonorrhoae

B) Treponema pallidum

C) Pasteurella pestis

D) Clostrldium botulinum.

• question_answer115) The process by which new alleles of a gene are produced is termed as

A) point mutation

B) gene manipulation

C) para mutation

D) forward mutation.

• question_answer116) Deposition of uric acid crystals within the synovial joint causes as

A) osteoarthritis

B) rheumatoid arthritis

C) gout

D) paralysis.

• question_answer117) Aromatic amines used in the manufacture of synthetic dyes cause cancer of the

A) skin

B) lung

C) liver

• question_answer118) Allergic reaction can be controlled by

A) antibiotics

B) histamines

C) antihistamines

D) none of the above.

• question_answer119) Hepatitis B is transmitted through

A) blood transfusion

B) intimate physical contact

C) sexually

D) all of the above.

• question_answer120) The hereditary disease in which the urine of a person turns black on exposure to air due to the presence of homogentisic acid is known as

A) ketonuria

B) phenylketonuria

C) haematuria

D) alkaptonuria.

• question_answer121) Centre for thermoregulation is located in

A) anterior pituitary

B) hypothalamus

C) kidney

D) heart.

• question_answer122) In prokaryotes, DNA replication occurs

A) at the time of cytokinesis

B) soon after cytokinesis

C) well before cytokinesis

D) long after cytokinesis.

• question_answer123) Which of the following is the abundant protein in human body?

A) haemoglobin

B) myoglobin

C) $\alpha -$keratin

D) collagen.

• question_answer124) In zoological nomenclature the sub-species is represented by

A) trinomen

B) binomen

C) uninomen

D) none of these.

• question_answer125) Miller and Ureys experiment in its created atmosphere employed

A) oxygen, ammonia, methane and water

B) hydrogen, ammonia, methane and water

C) hydrogen, ammonia, ethane and water

D) hydrogen, oxygen, nitrogen and water.

• question_answer126) Most fossils have been found in

A) black soil

B) lava flows

C) granite

D) sedimentary rocks.

• question_answer127) The Nobel Prize for medicine in 1998 was won by

B) Jon Watson

C) V.M. Ingram

D) Southerland.

• question_answer128) Coelomoducts are the excretory organs in

A) earthworm

B) Hydra

C) Planaria

D) none of these.

• question_answer129) Athletes generally suffer from

A) tachycardia

C) dyspnoea

D) cardiac arrythmias.

• question_answer130) Which of the following vitamins serves as a coenzyme in transamination and decarboxylation of amino acid?

A) pantothenic acid

B) folic acid

C) pyridoxine

D) niacin.

• question_answer131) Cholecystectomy (removal of gall bladder) results in

A) gastric cramps

B) impaired fat digestion

C) perpetual indigestion

D) no appreciable change.

• question_answer132) The protein most extensively studied in age-related changes is

A) myosin

B) actin

C) collagen

D) tubulin.

• question_answer133) In saltatory conduction of impulse

A) time is conserved

B) energy is conserved

C) both time and energy are conserved

D) neither time nor energy is conserved.

• question_answer134) Podocytes are associated with

A) muscle fibres

B) auditory canal

C) neuron

D) nephron.

• question_answer135) Excretion of potassium is governed primarily by

A) potassium reabsorption in proximal convoluted tubule

B) potassium secretion in proximal convoluted tubule

C) potassium secretion in distal convoluted tubule

D) potassium reabsorption in distal convoluted tubule.

• question_answer136) Ribosomes are made up of

A) $tRNA$ and protein

B) $rRNA$and protein

C) $mRNA$and protein

D) $mRNA$ and DNA.

• question_answer137) Duchenne muscular dystrophy, a sex-linked inheritance, is characterized by

A) sex ratio disorder

B) wasting away of muscles

C) inevitable death

D) all of the above.

• question_answer138) In transcription, anticodon is seen in

A) $tRNA$

B) $rRNA$

C) $mRNA$

D) DNA.

• question_answer139) In ECG, P-R interval corresponds to

A) time delay in$A-V$node

B) $S-A$nodal conduction time

C) increased ventricular contraction

D) time interval between onset of ventricular contraction.

• question_answer140) During oogenesis the second meiotic division occurs

A) before ovulation

B) after fertilization

C) just before fertilization

D) immediately after fertilization.

• question_answer141) Human eye is sensitive to wavelength in the range of

A) 300-390 nanometer

B) 380-760 nanometer a

C) 790-800 nanometer

D) 300-360 nanometer.

• question_answer142) Which of the hormones is a polypeptide

A) LH

B) FSH

C) insulin

D) thyroxine.

• question_answer143) Thyroid hormone has regulatory effect on

A) protein metabolism

B) carbohydrate metabolism

C) fat metabolism

D) all of the above.

• question_answer144) Which of the following is glycoprotein?

A) haemoglobin

B) casein

C) egg albumin

D) gelatin

• question_answer145) A complete catalytically active enzyme together with its coenzyme is termed as

A) apoenzyme

B) holoenzyme

C) isozyme

D) lysozyme.

• question_answer146) Excessive nutrient load in a water body leads to its

A) nitrification

B) eutrophication

C) glaciation

D) purification.

• question_answer147) The stable community structure of an ecosystem is termed as

A) dominant community

B) biocommunity

C) domicile factor

D) climax community.

• question_answer148) The Periyar sanctuary is famous for

A) elephants

B) wild bears

C) swamp deers

D) antelopes.

• question_answer149) The movement of oxygen from alveoli into the blood in pulmonary capillaries is through

A) active transport

B) facilitated transport

C) passive transport

D) none of these.

• question_answer150) Which of the following are osmoconformers?

A) bony fishes

B) elasmobranche

C) hagflshes

D) Lampreys.

• question_answer151) Specific proteins responsible for the flow of materials and information into the cell are called

A) membrane receptors

B) carrier proteins

C) integral proteins

D) none of these.

• question_answer152) Proteins that are embedded in the liqid layer of biomembranes are called

A) intrinsic

B) extrinsic

C) peripheral

D) none of these

• question_answer153) The fluid-mosaic model of biomembrane was proposed by

A) Waston and Crick

B) Singer and Nicholson

C) Danielli and Davson

D) none of the above

• question_answer154) The thickness of cell membranes varies between 6-9

A) millimeters

B) micrometers

C) nanometers

D) picometers

• question_answer155) The percentage of proteins in the mitochondrial membrane is

A) 20

B) 50

C) 80

D) 100.

• question_answer156) The$N{{a}^{+}}/{{K}^{+}}$pump transports

A) $3N{{a}^{+}}$into and$2{{K}^{+}}$out of cell

B) $2N{{a}^{+}}$into and$2{{K}^{+}}$out of cell

C) $3N{{a}^{+}}$out of and$3{{K}^{+}}$into cell

D) $3N{{a}^{+}}$ out and$2{{K}^{+}}$into cell.

• question_answer157) The bounding layer of protoplasm is called

A) ectoplasm

B) ectoderm

C) endoplasm

D) none of these.

• question_answer158) The maintenance of a steady and stable internal environment in an organism is called

A) equilibrium

C) homeostasis

D) all of these.

• question_answer159) One of the sciences for which training in biology is essential namely the science of treating diseases with drugs or curative substances, is called

A) pest control

B) physiotherapy

C) medicine

D) pharmacy.

• question_answer160) Roughly speaking, the ratio of present day species of plants to animals is

A) $\begin{matrix} 1.0 & 0.04 \\ \end{matrix}$

B) $\begin{matrix} 1.0 & 0.4 \\ \end{matrix}$

C) $\begin{matrix} 1.0 & 1.4 \\ \end{matrix}$

D) $\begin{matrix} 1.0 & 2.4 \\ \end{matrix}$

• question_answer161) As they release hydrolases that digest old and damaged cells, the term suicide bags is aptly used by cell biologists for

A) golgi bodies

B) lysosomes

C) glyoxisomes

D) peroxisomes.

• question_answer162) The conspicuous protein-storing layer of endosperm in cereal grains Contains

A) ribosomes

B) microbodies

C) aleurone grains

D) starch grains.

• question_answer163) Thread like protoplasmic projections on the free surface of absorptive cells (such as intestinal cells) are called

A) plasmodesmata

B) microfilaments

C) cilia

D) none of these.

• question_answer164) The space separating the two membranes around the nucleus is called

A) endonuclear space

B) exonuclear space

C) matric space

D) perinuclear space.

• question_answer165) The total number of cells in the human body is at least

A) ${{10}^{3}}$

B) ${{10}^{6}}$

C) ${{10}^{9}}$

D) none of these.

• question_answer166) The catalase-containing vesicles present in liver and leaf cells are called

A) glyoxisomes

B) lysosomes

C) peroxisomes

D) polyribosomes.

• question_answer167) Dictyosomes were discovered in 1989 by

A) Robert Brown

B) Rudolf Virchow

C) Robert Hooke

D) none of these.

• question_answer168) The two cell organelles not enclosed by a membrane are

A) chloroplast and mitochondrion

B) nucleus and nucleolus

C) golgi apparatus and microbodies

D) none of the above.

• question_answer169) The primary cells wall of plant consist of

A) cellulose

B) hemicellulose

C) pectin

D) all of these.

• question_answer170) The layer of cell wall common to two adjacent cell wall in plants is called

A) middle lamella

B) middle layer

C) common lamella

D) common layer.

• question_answer171) The symbiotic association of an algae and a fungus is called

A) mycorrhiza

B) fairy ring

C) lichen

D) none of these.

• question_answer172) Early and late blight of potato are caused respectively by

A) Fusarium and Claviceps

B) Gibberella and Penicillium

C) Aspergillus and Ustilago

D) none of the above.

• question_answer173) Fairy Rings in lawns result from outward- spreading circles of mycelia of mushrooms producing, at their periphery, fruiting bodies called

A) ascocarps

B) basidiocarps

C) sorocarps

D) pseudocarps.

• question_answer174) The phenomenon of sexual reproduction in zygomycetes, dependent upon the successful mating between$+$and$-$strains, is called

A) heterothallism

B) heterosis

C) heterospory

D) heterogamy.

• question_answer175) The number of known species of fungi is about

A) 1,000

B) 10,000

C) 1,00,000

D) 10,00,000.

• question_answer176) The rumen of cattle is the site of fermentation of cellulose fibres through the action of

A) archaebacteria

B) cyanobacteria

C) mycoplasmas

D) spirochaetes.

• question_answer177) An antibiotic not produced by one of the monera (Streptomyces) is

A) erythromycin

B) penicillin

C) streptomycin

D) tetracycline

• question_answer178) Gram negative heterotrophic bacteria that can biodegrade a variety of natural as well as man- made organic compounds, such as petroleum products, include

A) cyanobacteria

B) Clostridia

C) archaebacteria

D) none of these.

• question_answer179) Mycoplasmas are also called PPLO, which is an abbreviation of

A) pentose phosphate-led oxidation

B) parasitic prokaryote-like organisms

C) pleuropneumonia and plant-like organisms

D) pleuropneumonia-like organisms

• question_answer180) The most numerous and ancient, smallest and simplest microscopic organisms belong to which of the following kingdom?

A) bacteria

B) fungi

C) monera

D) plantae.

• question_answer181) Dodder (Cuscutta sp.) is an exceptional dicotyledon as it

A) is a parasite

B) is without leaves

C) lacks cotyledons

D) does not produce flowers.

• question_answer182) Chilghoza, a gymnosperm seed, that is eaten as a dry fruit is produced by

A) Pinus roxburgii

B) Pinus gerardiana

C) Ginkgo biloba

D) Cedrus deofara.

• question_answer183) The seed coat in both gymnosperms and angiosperms is derived from the

A) megaspore

B) microspore

C) megasporangium

D) microsporangium.

• question_answer184) Conifers have a definite advantage over other plants of the colder regions, due to their sustained photosynthetic activity, being

A) perennial

B) tall

C) evergreen

D) xerophytic.

A) Chlamydomonos

B) Spirogyra

C) Ulothrix

D) Volvox.

• question_answer186) The present day higher green plants are believed to have evolved from

A) ferns

B) green algae

C) liverworts

D) mosses.

• question_answer187) A few exceptional algae are parasitic. They include

A) Cephaleuros and Harveyella

B) Sargassum and Spirogyra

C) Ulothrix and Volvox

D) Chlamydomonas and Gelidinm.

• question_answer188) The commercially exploited algae include

A) Caulerpa, Chara and Volvox

B) Gelidium, Laminaria and Porphyra

C) Acetabularia, Spirogyra and Ulothrix

D) all of the above.

• question_answer189) The red colour of rhodophyta is due to the preponderance of

A) phycobilins

B) phycocyanin

C) phycoerythrin

D) none of these.

• question_answer190) Kingdom plantae comprises multicellular photoautotrophs that are

A) aquatic

B) epiphytic

C) terrestrial

D) all of these.

• question_answer191) The Chipko Movement for conservation of forests was started in 1972 in

A) North Kanara distric

B) Silent Valley

C) Sunderbans

D) Tehri-Garhwal.

• question_answer192) The government-sponsored programme for growing trees in towns and cities for aesthetic value is called

A) floriculture

B) agroforestry

C) social forestry

D) urban forestry.

• question_answer193) MAB of UNESCO stands for

A) man and biodiversity

B) maintenance of acquired biodiversity

C) movement for auxiliary biosphere

D) none of the above.

• question_answer194) The rate of formation of organic molecules in green plants or their populations is called

A) photosynthetic rate

B) net assimilation rate

C) gross primary productivity

D) net primary productivity.

• question_answer195) The natural cycles of carbon, oxygen, nitrogen, water, phosphorous, sulphur etc. are collectively called as

A) biochemical cycles

B) geochemical cycles

C) material cycles

D) none of the above.

• question_answer196) Recycling of matter occurs between the biotic and abiotic components of the biosphere during the formers

A) life

B) death

C) both [a] and [b]

D) neither [a] nor [b].

• question_answer197) With regard to materials, the earth and its atmosphere are a closed system. However, a little inflow of material does occur from outer space in the form of

A) UFOs

B) cosmic rays

C) meteros

D) all of these.

• question_answer198) Biosphere may be defined as

A) earths hydrosphere, lithosphere and atmosphere

B) a combination of all ecosystems of the earths environment

C) the entire inhabited part of the earth and its atmosphere, including living and non-living matter

D) all of the above

• question_answer199) Of the known flowering plants, the number of species of monocots is a partly

A) 5000

B) 50,000

C) 5,00,000

D) 555,00,000.

• question_answer200) The gymnosperms formed the dominant vegetation on the earth during the geological period called

A) carboniferous

B) permian

C) triassic

D) Jurassic.


text:
## Modeling in Identities

By making use of the feature of area calculation through multiplication, this is a visual way of showing that the result of multiplication is equal to the value of the area.

Multiplication and Area

$$\displaystyle 3.4$$ ; If we times 3 with 4, we will have found the area (the number of squares) within a rectangle, which has a length of 3 units.

Now, by using this feature, let’s form an identity using the area calculation.

🔻🔻Identities are expressions that are equal to one another. 🔻🔻

## Identical of $$\displaystyle (a+b)²$$

The square of anything is the multiplication of any number by itself. Let’s write it down within brackets next to one another.

$$\displaystyle (a+b)²=(a+b).(a+b)$$

This tells us;

If you are going to create a rectangular shape, one side will be $$\displaystyle a+b$$
and the other will also be $$\displaystyle a+b$$ . When we multiply them by one another $$\displaystyle (a+b).(a+b)$$ the area that is calculated is equivalent to our identity.

We have placed $$\displaystyle a+b$$ on either side, now let’s turn this into a rectangular area.

This area is going to give us our identity.

Let’s divide the area into pieces;

$$\displaystyle (a+b).(a+b)=(a+b)²$$

$$\displaystyle (a+b)²=a²+2ab+b²$$

## Identical of $$\displaystyle (a-b)²$$

$$\displaystyle (a-b)²=(a-b).(a-b)$$

I’m going to create a rectangular area and the length of either side will be $$\displaystyle a-b$$.

I need to subtract $$\displaystyle b$$ unit from a unit. I can do this by cutting ‘$$\displaystyle b$$ unit’ length from ‘$$\displaystyle a$$ unit’  length.

Let me take a square that has the side of a unit, in this way I will have created a side of $$\displaystyle a$$

The lengths of the sides are a and the area is $$\displaystyle a²$$.

Let me now cut ‘$$\displaystyle b$$ unit length’ from ‘$$\displaystyle a$$ unit length’ to create an ($$\displaystyle a-b$$) unit length.

Let’s cut this piece and throw it away.

The area that has been cut away:     $$\displaystyle a.b=ab$$

Let’s get rid of the area that has been cut from the complete square. I can reach an identical through ;

$$\displaystyle a²-ab$$

I still have been able to obtain the area I want, I continue,

Before I subtract, let me add an area as big as $$\displaystyle b²$$
next to the part I will be subtracting, this will give me an area that I can express easier $$\displaystyle (ab)$$

My identity now is as follows;

$$\displaystyle a²-ab+b²$$

We have subtracted $$\displaystyle ab$$ from  $$\displaystyle a²$$and added an area of $$\displaystyle b²$$.

Now, let’s cut the part that I need to subtract from the area including the area that I have added

My identity;

$$\displaystyle ab$$  area is also to be subtracted from my last identity;

$$\displaystyle a²-ab+b²-ab$$

If I organize

$$\displaystyle a²-2ab+b²$$

The final area that I have achieved;

$$\displaystyle a²-2ab+b²$$

## Identity of $$\displaystyle a²+b²$$

A square that has the length of $$\displaystyle b$$ ($$\displaystyle b²$$) is to be added to a square that has the length of $$\displaystyle a$$
(area $$\displaystyle a²$$)

I must find another way to express this area.

Let’s change the other length of this shape, change it to $$\displaystyle a+b$$ and turn it into a square.

I must subtract all white areas from the square $$\displaystyle (a+b)$$ .

$$\displaystyle (a+b).(a+b)-(ab+b²+ab-b²)$$
The total area of the square - The total area of the white areas

$$\displaystyle +b²$$ and $$\displaystyle -b²$$ simplifies each other.

$$\displaystyle (a+b).(a+b)-(ab+ab)$$

$$\displaystyle (a+b)²-2ab$$

Thus the identical is ;

$$\displaystyle a²+b²=(a+b)²-2ab$$

## Identity of $$\displaystyle a²-b²$$

When I subtract a $$\displaystyle b²$$ area from $$\displaystyle a²$$ , I must be able to express what is left behind in another way.

I must find another way to express this area.

I have cut the shape from the corner. I have obtained two equal trapezoids.

By turning one on its head, I have stuck it next to other one. I have obtained a rectangle.

The area of the rectangle :  $$\displaystyle (a-b).(a+b)$$

Thus;

$$\displaystyle a²- b²=(a-b).(a+b)$$

Let’s find this another way ;

The area is equal to the total area of these two rectangles.

$$\displaystyle a.(a-b) +b. (a-b)$$

Let me place the common multiplier in brackets, As $$\displaystyle (a-b)$$ is multiplied by both $$\displaystyle a$$ and $$\displaystyle b$$, it is the ‘common multiplier’.

$$\displaystyle a.(a-b) +b. (a-b) = ( a+ b) . ( a - b)$$

In earlier years, you had learnt the topic of distributive property of multiplication.

$$\displaystyle 3.(8+5) =3.8+3.5$$

We have been given the expression of 3.8 + 3.5 ; it’s as if we have placed the common  multiplier 3 within  parenthesis.

$$\displaystyle a²- b²= ( a+b) . (a -b )$$


text:
In this short post, I talk about why I’m moving away from using function apply.

With matrices

It’s okay to use apply with a dense matrix, although you can often use an equivalent that is faster.

N <- M <- 8000
X <- matrix(rnorm(N * M), N)
system.time(res1 <- apply(X, 2, mean))
##    user  system elapsed
##    0.73    0.05    0.78
system.time(res2 <- colMeans(X))
##    user  system elapsed
##    0.05    0.00    0.05
stopifnot(isTRUE(all.equal(res2, res1)))

“Yeah, there are colSums and colMeans, but what about computing standard deviations?”

There are lots of apply-like functions in package {matrixStats}.

system.time(res3 <- apply(X, 2, sd))
##    user  system elapsed
##    0.96    0.01    0.97
system.time(res4 <- matrixStats::colSds(X))
##    user  system elapsed
##     0.2     0.0     0.2
stopifnot(isTRUE(all.equal(res4, res3)))

With data frames

head(iris)
##   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
## 1          5.1         3.5          1.4         0.2  setosa
## 2          4.9         3.0          1.4         0.2  setosa
## 3          4.7         3.2          1.3         0.2  setosa
## 4          4.6         3.1          1.5         0.2  setosa
## 5          5.0         3.6          1.4         0.2  setosa
## 6          5.4         3.9          1.7         0.4  setosa
##   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
## 1 "5.1"        "3.5"       "1.4"        "0.2"       "setosa"
## 2 "4.9"        "3.0"       "1.4"        "0.2"       "setosa"
## 3 "4.7"        "3.2"       "1.3"        "0.2"       "setosa"
## 4 "4.6"        "3.1"       "1.5"        "0.2"       "setosa"
## 5 "5.0"        "3.6"       "1.4"        "0.2"       "setosa"
## 6 "5.4"        "3.9"       "1.7"        "0.4"       "setosa"

A DATA FRAME IS NOT A MATRIX (it’s a list).

The first thing that apply does is converting the object to a matrix, which consumes memory and in the previous example transforms all data as strings (because a matrix can have only one type).

What can you use as a replacement of apply with a data frame?

• If you want to operate on all columns, since a data frame is just a list, you can use sapply instead (or map* if you are a purrrist).

sapply(iris, typeof)
## Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species
##     "double"     "double"     "double"     "double"    "integer"
• If you want to operate on all rows, I recommend you to watch this webinar.

With sparse matrices

The memory problem is even more important when using apply with sparse matrices, which makes using apply very slow for such data.

library(Matrix)

X.sp <- rsparsematrix(N, M, density = 0.01)

## X.sp is converted to a dense matrix when using apply
system.time(res5 <- apply(X.sp, 2, mean))
##    user  system elapsed
##    0.78    0.46    1.25
system.time(res6 <- Matrix::colMeans(X.sp))
##    user  system elapsed
##    0.01    0.00    0.02
stopifnot(isTRUE(all.equal(res6, res5)))

You could implement your own apply-like function for sparse matrices by seeing a sparse matrix as a data frame with 3 columns (i and j storing positions of non-null elements, and x storing values of these elements). Then, you could use a group_by-summarize approach.

For instance, for the previous example, you can do this in base R:

apply2_sp <- function(X, FUN) {
res <- numeric(ncol(X))
X2 <- as(X, "dgTMatrix")
tmp <- tapply([email protected], [email protected], FUN)
res[as.integer(names(tmp)) + 1] <- tmp
res
}

system.time(res7 <- apply2_sp(X.sp, sum) / nrow(X.sp))
##    user  system elapsed
##    0.03    0.00    0.03
stopifnot(isTRUE(all.equal(res7, res5)))

Conclusion

Using apply with a dense matrix is fine, but try to avoid it if you have a data frame or a sparse matrix.


text:
Exporting Summary Boxes

I would like to Export a Summary Box in its expanded Form. How do i do this? I can Export a collapsed Summary Box by doing:

result = ConvolutionLayer[4,8] (*which is a summary Box*)
Export["testFile.pdf", result]

• Interactively you can expand the summary box and then right-click on the cell bracket and select "Save selection as", but it would be nice to be able to do that programmatically – Jason B. Feb 5 '19 at 18:00

edit: simplified code and an explanation

I could bet I already answered that in the past but can't find. The solution works as follows:

What you see is a box expression (MakeBoxes[result of evaluation]) rendered by the FrontEnd. You can inspect it via Ctrl+Shift+E or by applying ToBoxes on your expression. The latter allows you to work with boxes and modify them.

After inspection we see that it is roughly DynamicModule[{open = False}, PaneSelector[...].... So we want to replace False with True in order to make the initial pane open. You can later use RawBoxes or DisplayForm to preview results or to make Export export its rendered form instead of raw box expression.

result = ConvolutionLayer[4,8];

result //
ToBoxes //
ReplaceAll[ HoldPattern[Typesetopen = _] :> (Typesetopen = True)] //
RawBoxes //
Export["test.pdf", #] &

• Unevaluated also works for this, ReplaceAll[ HoldPattern[Typesetopen = False] :> Unevaluated[Typesetopen = True]] – Jason B. Feb 5 '19 at 18:13
• @JasonB. Good for you :p I find it hard to use Unevaluated for more than simple things so I don't use it ;) – Kuba Feb 5 '19 at 18:17
• This is in a Hold... structure so you don't even need to Hold. You can just do something like HoldPattern[Typesetopen = _] :> (Typesetopen = True) – b3m2a1 Feb 5 '19 at 21:10
• @b3m2a1 you are right, guess I shouldn't have skipped my 3rd coffee. Will correct it tomorrow. – Kuba Feb 5 '19 at 21:14
• @Kuba Thanks for giving me this insight. Do you also know how i can ommit the ConvolutionLayer[]? – Gladaed Feb 28 '19 at 17:24