Question

Under identical conditions of temperature, the density of a gas X is three times that of gas Y while molecular mass of gas Y is twice that of X. The ratio of pressures of X and Y will be

• A. 6
• B. 1/6
• C. 2/3
• D. 3/2

Answer 1

Answer: (A)

6

Answer 2

ρ = $\frac{PM}{RT}$ ⇒ P = $\frac{\rho RT}{M}$

P_x = $\frac{\rho_{x}RT}{M_{x}}$

P_y = $\frac{\frac{\rho_{x}RT}{3}}{2M_{x}}$

6 P_y = $\frac{\rho_{x}RT}{M_{X}}$∴ 6 P_y = P_x

$\frac{P_{X}}{P_{Y}} = 6$