What will be the minimum pressure required to compress $500 \, dm^{3}$ of air at $1 \, bar$ to $200 \, dm^{3}$ at $30^{\circ} C$ (in $, bar$)?

The correct combined gas law equation is:

$A$ mass of gas occupies $11.2 \ dm^3$ at $105 \ kPa$. What is its volume if the pressure is increased to $210 \ kPa$ at constant temperature (in $dm^3$)?

Which one of the following indicates the correct value of the gas constant $R$?

Air entering the lungs ends up in tiny sacs called alveoli. It is from the alveoli that oxygen diffuses into the blood. The average radius of the alveoli is $0.0050 \ cm$ and the air inside contains $14$ per cent oxygen. Assuming that the pressure in the alveoli is $1.0 \ atm$ and the temperature is $37 \ ^oC$,calculate the number of oxygen molecules in one of the alveoli.

If the density of a gas at $27\,^{\circ}C$ and $2\, atm$ is $5.46\, g/L$,then calculate the density of the gas at $STP$. (in $, g/L$)