<unk>  is the chemical compound with the formula AsH3.  This flammable, pyrophoric, and highly toxic gas is the simplest compound of arsenic.  Aside from its lethality, it finds applications in the semiconductor industry and for the synthesis of organoarsenic compounds.
At its standard state,<unk>  is a colorless, denser-than-air gas that is soluble in water (200 mL/L) and in many organic solvents as well. Whereas<unk>  itself is odorless, owing to its oxidation by air it is possible to smell a slight, garlic-like scent when the compound is present at about 0.5 ppm.  This compound is generally regarded as stable, since at room temperature it decomposes only slowly.  At temperatures of ca. 230 °C decomposition to arsenic and hydrogen is rapid. Several factors, such as humidity, presence of light and certain catalysts (namely aluminium) facilitate the rate of decomposition.
AsH3 is a pyramidal molecule with H–As–H angles of 91.8° and three equivalent As–H bonds, each of 1.519 Å length.  The term<unk>  is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl or alkyl.  For example, As(C6H5)3, called triphenylarsine, is referred to as "an<unk> ."
Arsine
Nitrazine
Triphenylmethane
Cyclochlorotine
Methanol
Vinyl chloride
Anethole
Lindane