The unit of pressure is Pa.

The pressure P of a fixed mass of gas is directly proportional to its volume V, provided that the temperature of the gas remains constant.

The volume of a fixed mass of gas is halved if the temperature in Kelvin scale is doubled, provided that the pressure of the gas remains constant.

We can determine the absolute zero temperature by extrapolating the P-T graph or V-T graph of a gas in Celsius scale.

The pressure of a fixed mass of gas will decrease if both the temperature and volume are doubled.

Brownian motion of smoke particles is caused by the bombardments between themselves.