4. In an isothermal reversible expansion, if the volume

of 96 gm of oxygen at 27°C is increased from 70 litres to 140 litres, then the work done by the gas will be

(a)      300 R log_10²               (b) 81 R log_e²

(c)      900 R log_10²                (d) 2.3 x 900 R log_10²

Ans. d