If $4 \ g$ of oxygen gas diffuses through a fine hole,how many grams of hydrogen gas will diffuse under the same conditions?

The variation of pressure with volume of a gas at different temperatures can be graphically represented as shown in the figure. On the basis of this graph,answer the following questions:
$(i)$ How will the volume of a gas change if its pressure is increased at constant temperature?
$(ii)$ At a constant pressure,how will the volume of a gas change if the temperature is increased from $200 \ K$ to $400 \ K$?

The rate of diffusion of methane at $1.0 \ atm$ pressure is twice that of another gas '$X$' kept at $1.45 \ atm$. The molecular weight of the gas '$X$' is
[$T$ kept constant]

When $0.0168 \, mol$ of $O_2$ obtained from the decomposition of $KClO_3$ is collected over water at $25 \, ^\circ C$,the volume is $428 \, mL$ and the pressure is $754 \, mm$. What is the water vapor pressure at $25 \, ^\circ C$ in $mm$?

Which of the following statements is correct?

For a liquid,the normal boiling point is $-173\,^{\circ}C$. At $2\ atm$ pressure,its boiling point should be nearly ......... $^{\circ}C$. (Given: $\Delta H_{vap} = 200\ cal/mol$,$R = 2\ cal/mol\cdot K$,$\ln 2 = 0.7$)