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)/(0.080) = 75 cm^(3) mol^(-1)`,
`b =( V_(c))/( 3) =25 cm^(2) mol^(-1) = 0.025 L mol^(-1)`
`T_(c ) =(8a)/( 27 Rb) `
`( 4 xx 10^(5))/( 821) =(8 xx a)/( 27 xx 0.0821 xx 0.025) rArra =3.375`