Vapour density of a compound is defined as the ratio of mass of a certain volume of gas to the mass of the same volume of hydrogen gas under conditions of temperature and pressure.
Vapour density`=("Mass of certain of gas"(22.4L)"at STP")/("Mass of same volume of" H_(2) "gas"(22.4L)"at STP")`
`=(Mw)/(2)`
i.e., Molecular mass of gas=Vapour density `xx2`
Vapour density is a unitless quantity it is unaffected by variation of temperature and pressure.
Let `NH_(4)HS(s)hArrNH_(3)(g)+H_(2)S(g)`
The vapour density of the mixture will be:

Options

A. equal to that of `NH_(4)HS`
B. lesser than that of `NH_(4)HS`
C. greater than that of `NH_(4)HS`
D. cannot be predicted.

Answer

B