What is the relationship between viscosity and pressure?

The rate of diffusion of a gas is ..... times that of hydrogen. (Molecular weight = $98$)

The rate of effusion of a gas is directly proportional to.....

Gas $X$ diffuses three times faster than gas $Y$. What is the ratio of their densities,i.e.,$D_x : D_y$?

$A$ container consists of a mixture of $28 \ g \ N_2$,$8 \ g \ He$,and $40 \ g \ Ne$ at $25^{\circ} C$. If the total pressure exerted by the gaseous mixture is $20 \ bar$,what is the partial pressure exerted by $N_2$ (in $bar$)?

Mechanical work is especially important in systems that contain