Mechanical work is especially important in systems that contain

The $O_2$ gas is collected over water at $400 \ K$ temperature in a $2 \ L$ vessel. If the total pressure of the mixture is $33.26 \ bar$ and the pressure of dry $O_2$ gas is $32.20 \ bar$,find the vapour pressure of water under the same conditions.

Which of the following property of a small drop of mercury can be used to explain the spherical shape of mercury droplets?

At $27^{\circ} C$, a closed vessel contains a mixture of equal weights of helium (mol. wt. = $4$), methane (mol. wt. = $16$) and sulphur dioxide (mol. wt. = $64$). The pressure exerted by the mixture is $210 \ mm$. If the partial pressures of helium, methane and sulphur dioxide are $p_1, p_2$ and $p_3$ respectively, which one of the following is correct?

$A$ gas diffuses $1/3$ times as fast as hydrogen. Its molecular weight is

At higher altitudes,the boiling point of water lowers because: