Answer: Boyle's law.
Explanation:
Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.
[tex]P\propto \frac{1}{V}[/tex] (At constant temperature and number of moles)
[tex]P_1V_1=P_2V_2[/tex]
where,
[tex]P_1[/tex] = initial pressure of gas
[tex]P_2[/tex] = final pressure of gas
[tex]V_1[/tex] = initial volume of gas
[tex]V_2[/tex] = final volume of gas
Therefore, the law which states the volume of a gas is inversely proportional to the absolute pressure applied to it when the temperature is kept constant is Boyle's law.