Under isothermal condition, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is : [Given that 1 L bar = 100 J]

Options

A. 30 J
B. `-30`J
C. 5 kJ
D. 25J

Answer

B

Explanation

`W_("irr") = - P_("ext") Delta V`
`= -2 "bar " xx (0.25 - 0.1)L = -2 xx 0.15L`- bar
= 0.30 L -bar = `-0.30 xx 100J= -30J`