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), (4xx 10^(5))/(821)= (8a)/(27xx 0.0821 xx 0.025) implies a= 3.375`.