Two vessels separately contain two ideal gases A and B at the same temperature, the pressure of A being twice that of B. Under such conditions, the density of A is found to be 1.5 times the density of B. The ratio of molecular weight of A and B is

According to an ideal gas equation, the molecular weight of an ideal gas isM=ρRTP   as P=ρRTMwhere P, T and ρ are the pressure, temperature and density of the gas respectively and  R  is the universal gas constant.∴ The molecular weight of A isMA=ρARTAPAand that of B isMB=ρBRTBPB Hence, their corresponding ratio is MAMB=ρAρBTATBPBPA Here, ρAρB=1.5=32,TATB=1 and PAPB=2∴  MAMB=32(1)12=34