I am having confusion with the follow two sentences. Currently I am preparing
JLPT N5 so please answer accordingly (I can't understand very advanced
explanations).

> 私は日曜日国へ帰ります
>
> 私は誕生日に国へ帰ります

So there are expressions of time where we should use に and some where we
shouldn't . Can anyone classify for which expressions of time we should に
particle and where we shouldn't. I read that for specific "time" we should use
に but then also it seems like 日曜日 is a specific time. So why are we not using
に particle here. These examples are from a book.
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2015-09-27T06:17:19.323
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2015-09-28T08:24:01.957
2020-06-17T08:18:27.500
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question
particles particle-に
Almost similar looking sentences with and without に particle
Check these sentences which I wrote in English below.

> 私は日曜日国へ帰ります → I will go to (my or someone's) country on (this, next or
> someday) Sunday.  
>  私は誕生日に国へ帰ります → I will go to (my or someone's) country at (my or someone's)
> birthday.

As you can see my sentences, these Japanese sentences have some unclear
points. In short, these are lack of "whose?" and "when?".

If I write Japanese sentence, for example, it is below:

> I will go to my country on next Sunday. → 私は次の日曜日に自分の国へ帰ります。  
>  I will go to my country at my mother's birthday. → 私は私の母の誕生日に自分の国へ帰ります。

Hope it helps.

Thanks
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2015-09-27T08:20:35.157
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2015-09-27T08:36:01.897
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It's said that words that mean absolute time are accompanied with に while
relative ones are not.

今日、きのう、明日、今週、先週、来週 or 今年 are ones that are used without に to indicate when
something occurs. (Of course, they can be an (indirect) object in a sentence
like (予定を)今日にする, besides that.)

日曜日 or 週末 are ones that might take に.

誕生日 or ◯月◯日 are ones that almost always call for に.
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2015-09-27T14:35:35.367
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2015-09-27T14:40:37.933
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answer
Both sentences are OK.

The difference is the 1st one is more colloquial.
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answer