# Densities of two gases of same molecular weight are in the ratio 1:2 and their temperature are in the ratio 2:1 then the ratio of their respective pressures is

$(a)\;1:1\qquad(b)\;1:2\qquad(c)\;2:1\qquad(d)\;4:1$

$PV = \large\frac{w}{m}RT$
$P = \large\frac{d}{m}RT$
$P_1 = \large\frac{d_1}{m_1}RT_1$
$P_2 = \large\frac{d_2}{m_2}RT_2$
$\therefore \large\frac{P_1}{P_2} = \large\frac{d_1}{d_2}\times\large\frac{T_1}{T_2}$
$\Rightarrow \large\frac{1}{2}\times\large\frac{2}{1}$
$\Rightarrow 1$