The density of air is higher at sea level. This fact is a practical application of which law?

The root mean square velocity of an ideal gas in a closed container of fixed volume is increased from $5 \times 10^4 \ cm \ s^{-1}$ to $10 \times 10^4 \ cm \ s^{-1}$. Which of the following statements correctly explains how the change is accomplished?

The volume of a given amount of gas at $27^{\circ} C$ at constant pressure is $420 \ cm^3$. If the temperature is reduced by $20^{\circ} C$ at constant pressure,what will be the volume of the gas (in $cm^3$)?

The following graphs are based on Boyle's Law at constant mass and temperature. Describe what each graph represents.

If $28 \ g$ of $N_2$ gas occupies a volume of $10 \ L$ at a pressure of $2.46 \ atm$,the temperature will be ......... $K$.

$A$ 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 $dm^3$)?