[By Lussac’s law]

N_{2} + 3H_{2} → 2NH_{3}

1 vol : 3 vol → 2 vol

1 lit : 3 lit → 2 lit

To calculate the volume of ammonia formed when only 10% conversion takes place,

∴ 10 % of 2 lit = 10\over 100 ×2 = 0.2 lit

Hence, **volume of ammonia formed is 0.2 lit or 20% or 1/5th of vol of N _{2} and H_{2}**