Question

Two vessels separately contain two ideal gases A and B at the same temperature. The pressure of A is 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 weights of A and B is ______.

Options

• 2

• `3/4`

• `1/2`

• `2/3`

Answer 1

Two vessels separately contain two ideal gases A and B at the same temperature. The pressure of A is 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 weights of A and B is `underline(3/4)`.

Explanation:

For ideal gas, PV = RT   M = ρV

`therefore"PM"/rho="RT"`

`therefore("P"_"A""M"_"A")/rho_"A"=("P"_"B""M"_"B")/rho_"B"`

`"M"_"A"/"M"_"B"=rho_"A"/rhp_"B"xx"P"_"B"/"P"_"A"=3/2xx1/2=3/4`