When the volume of a system is increased two times and the temperature is decreased to half of its initial temperature,then the pressure becomes ...... times.

$A$ sample of $O_2$ gas has a volume of $100 \ ml$ at a pressure of $1 \ atm$ and a temperature of $27^{\circ}C$. If the pressure is increased to $2 \ atm$ while the volume remains $100 \ ml$,the new temperature will be .... $^{\circ}C$.

$12\,g$ of gas occupies a volume of $4\times 10^{-3}\,m^3$ at a temperature of $7\,^oC$. After the gas is heated at constant pressure,its density becomes $6\times 10^{-4}\,g/cc$. Find the temperature $T$ (in $K$) to which the gas was heated.

Consider a $1 \, cm^3$ sample of air at absolute temperature $T_0$ at sea level and another $1 \, cm^3$ sample of air at a height where the pressure is one-third atmosphere. The absolute temperature $T$ of the sample at that height is

What is the ratio of the universal gas constant $(R)$ to the Avogadro number $(N_A)$?

$A$ vessel has $8 \ g$ of oxygen at pressure $P$ and temperature $400 \ K$. $A$ small hole is made in it so that oxygen leaks out. How many grams of oxygen leak out if the final pressure is $P/4$ and the temperature is $200 \ K$?