At constant temperature,$200 \ cm^3$ of $N_2$ at $720 \ mm$ pressure and $400 \ cm^3$ of $O_2$ at $750 \ mm$ pressure are taken in a $1 \ L$ flask. What will be the total pressure of the mixture in $mm$?

Consider the following statements:
$Statement-I$ : If the intermolecular forces are stronger than thermal energy,the substance prefers to be in a gaseous state.
$Statement-II$ : Among all elements,the total number of elements available as gases at room temperature is $10$.

At $300 \ K$ and $760 \ torr$ pressure, the density of a mixture of $He$ and $O_2$ gases is $0.543 \ g \ L^{-1}$. The mass percent of oxygen is approximately $(R = 0.0821 \ L \ atm \ K^{-1} \ mol^{-1})$

If the rate of diffusion of a gas having twice the molecular mass of nitrogen is $56 \ mL \ s^{-1}$,then the rate of diffusion of nitrogen will be ........... $mL \ s^{-1}$.

Mixing of two different ideal gases under isothermal reversible conditions will lead to:

Which of the following gas mixtures is not applicable for Dalton's law of partial pressure?