Question

Two separate bulbs contain ideal gases A and B. The density of gas is twice that of gas B. The molecular mass of gas A is half that of gas B. The two gases are at the same temperature. The ratio of pressure of A that of gas B is?

• A. 2
• B. 1/2
• C. 4
• D. 1/4

Answer 1

The correct option is C 4

solution:

To find density :-$(PM=DRT)$

$(\therefore D=\frac{PM}{RT})$

Given :- $(D_1=2D_2$)

$(M_1=\frac{1}{2}{M}_2$)

$(T_1=T_2$)

$(\frac{D_1}{D_2}=2$)

$(\frac{M_1}{M_2}=\frac{1}{2}$)

Now $(D=PM$)

$(\because R\&T$) are constant)$(\frac{D_1}{D_2}=\frac{P_1{M}_1}{P_2{M}_2}$)

$(2=\frac{P_1}{P_2}\times \frac{1}{2}$)

$(2\times 2=\frac{P_1}{P_2})$

$(\therefore \frac{P_1}{P_2}=4$)

hence the correct option: is C