Question

A and B are ideal gases. The molecular weights of A and B are in the ratio of 1 : 4 . The pressure of a gas mixture containing equal weights of A and B is P atm. What is the partial pressure (in atm) of B in the mixture?

• A. P/5
• B. P/2
• C. P/2.5
• D. 3P/4

Answer 1

The correct option is A

P/5

Equal weights of two compounds taken

$\frac{P_1}{P_2}=\frac{M_2}{M_1}$

$\frac{P_A}{P_B}=\frac{M_B}{M_A}=\frac{4}{1}$

$P_B=\frac{1}{5}\times P$