The density of a gas is `1.964 g dm^(-3)` at 273 K and 76 cm Hg. The gas is

Options

A. `CH_(4)`
B. `C_(2)H_(6)`
C. `CO_(2)`
D. Xe

Answer

C

Explanation

From ideal gas equation, PV = nRT
or, `PV=(w)/(M)RT` or, `M=(w)/(V).(RT)/(P)=d(RT)/(P)`
`d=1.964 g//dm^(3)=1.964xx10^(-3)` g/cc
P = 76 cm = 1 atm
R = 0.0821 lit. atm `K^(-1)mol^(-1)`
= 82.1 cc atm `K^(-1)mol^(-1)`
T = 273 K
`therefore M = (1.964xx10^(-3)xx82.1xx273)/(1)=44`
The molecular weight of `CO_(2)` is 44.