Which of the following is not considered in the calculation of the rate of diffusion according to Graham's Law?

Equal amounts of two gases of molecular weights $4$ and $40$ are mixed. The pressure of the mixture is $1.1 \ atm$. What will be the partial pressure of the lighter gas in the mixture (in $atm$)?

It takes $38 \, s$ for $1 \, mol$ of $N_2$ gas to effuse through a pinhole at a pressure of $0.8 \, atm$. It takes $57 \, s$ for $1 \, mol$ of an unknown gas $X$ to effuse through the same pinhole at a pressure of $1.6 \, atm$. Calculate the molar mass of $X$.

$5$ moles of a gas is allowed to pass through a series of changes as shown in the graph,in a cyclic process. The processes $C \rightarrow A$,$B \rightarrow C$ and $A \rightarrow B$ respectively are

$A$ sample of air contains $N_2, O_2$ and $H_2O$. It is saturated with water vapor and the total pressure is $640 \, torr$. The vapor pressure of water is $40 \, torr$ and the molar ratio of gases ${N_2}:{O_2}$ is $3:1$. What is the partial pressure of $N_2$ in the sample in $torr$?

Explain the term 'laminar flow'. Is the velocity of molecules same in all the layers in laminar flow? Explain your answer.