The number of molecules in a litre of a gas at temperature of 27°C and a pressure of 106 dyne cm-2 is [UP CPMT 2013]

The number of molecules (n) in a volume (V) at pressure p and temperature T is given by                                   n=pVkBTHere, p = 106 dyne cm-2, V = 100 cm3,          T = 273 + 27 = 300 K,           kB= 1.38 × 10-16 erg per kelvin∴        n=106(1000)1.38×10-16×300≈2.4×1022