X and Y are two volatile liquids with molar weights of $10\; g\; mol^{–1}$ and $40\; g\; mol^{–1}$ respectively. Two cotton plugs, one soaked in X and the other soaked in Y, are simultaneously placed at the ends of a tube of length $L = 24\; cm$, as shown in the figure. The tube is filled with an inert gas at 1 atmosphere pressure and a temperature of $300\; K$. Vapours of X and Y react to form a product which is first observed at a distance d cm from the plug soaked in X. Take X and Y to have equal molecular diameters and assume ideal behaviour for the inert gas and the two vapours.The experimental value of d is found to be smaller than the estimate obtained using Graham’s law. This is due to:

Question

$\begin{array}{1 1} \text{larger mean free path for X as compared to that of Y.} \\ \text{larger mean free path for Y as compared to that of X} \\ \text{ increased collision frequency of Y with the inert gas as compared to that of X with the inert gas.} \\ \text{increased collision frequency of X with the inert gas as compared to that of Y with the inert gas} \end{array} $