For the same mass of two ideal gases X and Y at the same temperature and pressure, the volume of Y is found to be three times as large as that of X. compare the values of their molar masses.

Explanation

`P_(X)=P_(Y),T_(X)=T_(Y),3V_(X)=V_(Y)`
According to ideal gas equation, `P_(X)V_(X)=n_(X)RT_(X) and P_(Y)V_(Y)=n_(Y)RT_(Y)`
i.e., `(P_(X))/(P_(Y))xx(V_(X))/(V_(Y))=(n_(X))/(n_(Y))xx(T_(X))/(T_(Y)) or, (1)/(3)=(n_(X))/(n_(Y))`
Let, molar masses of X and Y are `M_(X) and M_(Y)` respectively.
`therefore (w//M_(X))/(w//M_(Y))=(1)/(3) or, (M_(X))/(M_(Y))=3`.