Question

Two vessel separately contains 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
A. `1//2`
B. `2//3`
C. `3//4`
D. 2

Answer 1

Correct Answer - C
Here, `rho_(A) = 1.5 rho_(B)` or `rho_(B)` . Also `P_(A) = 2 rho_(B)`
As, `P = (RT rho)/(M) :. P_(A) = (Rtrho_(A))/(M_A), P_(B) = (RT rho_(B))/(M_B)`
`(P_A)/(P_B) = (rho_(A) xx M_(B))/(rho_(B) xx M_(A)) or (M_A)/(M_B) = (rho_A)/(rho_B) xx (P_B)/(P_A)`
`(M_A)/(M_B) = 3/2 xx 1/2 = 3/4`.