Given:
Density, d = 1.964
g∕dm3 =
g =
1.964×10−3 g/cc (1 dm = 10 cm)
Temperature, T = 273 K
Pressure, P = 76 cm Hg
76 cm = 760 mm = 1 atm (Since 1 cm = 10 mm and 760 mm = 1 atm)
Gas constant, R = 0.0821 L
atmK−1mol−1 = 0.0821 ×
103 cc
atmK−1mol−1 (Since 1L =1000 cc)
= 82.1 cc
atmK−1mol−1 Now, ideal gas equation is:
PV = nRT
where, n = Number of moles
Let given mass of the gas be 'W' g and molar mass be 'M' g.
PV =
RT (Since, no. of moles =
Givenmass∕Molarmass)
M =
=
d. (density =
W∕V)
Substituting all the value in the above equation, we get
M =
= 44 g/mol
Thus, the gas is
CO2, as the molar mass of
CO2 is 44 g/mol.
Hence, option 'C' is correct.