For a real gas (mol. Mass = 60) if density at critical point is `0.80 g"/"cm^(3)` and its `T_(c ) = (4xx 10^(5))/(821)K`, then van der Waal's 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) = 75 cm^(3) mol^(-1) , b = (V_(c))/(3) = 25 cm^(3) mol^(-1) = 0.025 L mol^(-1)`
`therefore T_(c) = (8a)/(27 Rb) , (4 xx 10^(5))/(821) = (8 xx a)/(27 xx 0.0821 xx 0.025) implies a = 3.375`