$O_2$ gas is filled in a cylinder. If the pressure is doubled and the temperature is quadrupled,what will be the factor by which the density changes?

At a room temperature of $23^{\circ}C$,a person inhales $1500 \, ml$ of air at a body temperature of $37^{\circ}C$. If the pressure and mass remain constant,what will be the volume of the air in the person's lungs in $ml$?

The volume of a given mass of a gas at $27^{\circ} C$ and $1$ $atm$ is $100$ $cc$. What will be its volume at $327^{\circ} C$ if the pressure remains constant (in $cc$)?

Estimate the total number of air molecules (inclusive of oxygen,nitrogen,water vapour,and other constituents) in a room of capacity $25.0 \; m^{3}$ at a temperature of $27^{\circ} C$ and $1 \; atm$ pressure.

At constant temperature, the pressure of a gas is decreased by $20 \%$. What is the percentage change in volume?

When $2 \, g$ of a gas are introduced into an evacuated flask kept at $25 \, ^\circ C$,the pressure is found to be $1 \, atm$. If $3 \, g$ of another gas is added to the same flask,the pressure becomes $1.5 \, atm$. The ratio of the molecular weights of these gases will be: