What are the equivalent volumes of hydrogen, oxygen and nitrogen?

Explanation

Equivalent volume is the volume occupied by one equivalent of any gas at NTP.
We know, 1 mole of molecules of any gas at NTP occupies 22-4 litres and 1 mole of atoms of any diatomic gas at NTP occupies 11-2 litres.
Now,
1 mole of H contains 1 equivalent of H,
1 mole of O contains 2 equivalents of O,
1 mole of N contains 3 equivalents of N.
Thus at NTP,
1 equivalent of H occupies 11.2 litres,
1 equivalent of O occupies `(11.2)/( 2) = 5.6` litres,
1 equivalent of N occupies `(11.2)/( 3) = 3.73` litres.