40. The volume of an ideal gas is 1 litre and its pressure is equal to 72cm of mercury column.

The volume of gas is made 900 cm3 by compressing it isothermally. The stress of the gas will be (a)  8 cm (mercury)                 (b)  7 cm (mercury) (c)   6 cm (mercury)                (d)  4 cm (mercury) Ans. a (5)