Question

22. The density of a gas is 1.964 g / dm-3 at 273 K and 76 cm Hg. The gas
is
1) CH4
2) CO₂
3) Xe
4) C₂H6
​

Answer 1

C02

Explanation:

pV=nRT or pv= (w/M)RT or M= (w/v)(RT/p)

Therefore, M=d (RT/p)

Here, d=1.964g/dm^3 =1.964×10^−3 g/cc

P = 76 cm = 760 mm Hg = 1 atm

R = 0.0821 L atm K^−1 mol ^−1

=82.1 cc atmK ^−1 mol ^−1

T=273K

∴M= (1.964×10^−3 ×82.1×273)/1 = 44g/mol

The molecular weight of CO2is 44.

So, the gas is CO2

.