**Boyles’ law : **

For a fixed mass of gas at a constant temperature,

P_{1}V_{1}= P_{2}V_{2} = K = constant

**Charles’ law :**

For a fixed mass of gas at constant pressure,

V_t=V_o({1 \pm {t\over273}})or {V_1\over T_1}={V_2\over T_2} = constant (k)

**Gay-Lussac’s Law :**

For a fixed mass of gas at constant volume,

or {P_1\over T_1}={P_2\over T_2} = constant (k)

**The combined form of Boyle’s Law and Charles’ Law :**

For a fixed mass of gas when P and T vary,

{P_1V_1\over T_1}={P_2V_2\over T_2} = constant (k)**E****quation of state for an ideal gas :**

For n mole of an ideal gas, PV = nRT

Relationship between temperature in Celsius and absolute scale :

t°C = (273 +t) K = T K.