Two containers $A$ and $B$ contain $\mathrm{CO}_2$ gas. Pressure, volume and absolute temperature of the gas in $A$ are 4 times more compared to that in $B$. The mass of the gas in $B$ is $x \mathrm{~g}$, then the mass of the gas in $A$ will be

The rate of diffusion of a gas $A$ is $\sqrt{5}$ times more than that of gas $B$. If the molar mass of $A$ is $x \mathrm{~g} \mathrm{~mol}^{-1}$, the molar mass of $B$ (in $\mathrm{g} \mathrm{mol}^{-1}$ ) is

4 g of an ideal gas $A$ (molar mass $=M_A$ ) present in a vessel of volume $V$ litre exerted a pressure of 5 atm at 300 K . When 16 g of another ideal gas $B$(molar mass $=M_B$ ) was introduced into this vessel at the same temperature, its pressure increased to 10 atm . What is the correct relationship between $M_A$ and $M_B$ ?