The mean indoor airborne Chloroform `(CHCl_3)` concentration in a room was determined to be `0.4 mug//m^3.` Use the following data : T =293 K,
P = 1 atmosphere, R = `82.05 xx 10^-6 a t m.m^3//m o l -K, ` Atomic weights : C = 12, H = 1, Cl = 35.5. This concentartion expressed in parts per billion (volume basis,ppbv) is equal to