For a real gas (mol.mass =60) if density at critical point is `0.80g//cm^(-3)` and its `T_(c)=(4xx10^(5))/(821)K,` then van der Waals' constant a ( in atm `L^(2)mol^(-2)`) is

Options

A. 0.3375
B. 3.375
C. 1.68
D. 0.025

Answer

B

Explanation

`V_(c)=60/(0.80)=75cm^(3)mol^(-1)`
`b=(V_(c))/3=25cm^(3)mol^(-1),=0.25Lmol^(-1)`
`thereforeT_(c)=(8a)/(27Rb)`
`(4xx10^(5))/(821)=(2.45)/(0.425)=5.76 gL^(-1)`
`rArra=3.375`