Question

What is the relation between pressure, temperature and volume?

Answer 1

This can be shown by the gas equation ${\text{PV = nRT}}$ , here, ${\text{P}}$ is pressure , ${\text{V}}$ is volume and ${\text{T}}$ is temperature. This law is a combination of Boyle’s law, Charles law and Avogadro’s law.
Combination of these equations states about ideal gases.

Complete answer: Avogadro’s law: This law states that ratio of volumes of gases is directly proportional to the ratio of their number of moles at constant pressure and at absolute temperature.
$\dfrac{{{V_1}}}{{{V_2}}}\, = \,\dfrac{{{n_1}}}{{{n_2}}}$
Charles law: This law states the following equation:
$\dfrac{{{V_1}}}{{{T_1}}}\, = \,\dfrac{{{V_2}}}{{{T_2}}}$ , at constant pressure throughout the experiment. This is also for ideal gas.
Boyle's law: This law states the following equation:
${P_1}{V_1}\, = \,{P_2}{V_2}$ , at constant temperature.
Combination of the above three equations gives us:
${\text{PV = nRT}}$
The above equation gives us the relation between temperature, pressure and the volume.

Note:
Here the main point to note is that this equation is only for ideal gas not for any real gas. For real gases this equation can be modified. Similarly liquids have also a relation similar to gases. You should remember above equations Boyle's law, Charles law and Avogadro's law to prove the ideal gas equation.