Question

The number of litres of air (containing 20% by volume of oxygen) needed for the complete combustion of 4.0 litres of acetylene at a given temperature and pressure is

(a) 4

(b) 10

(c) 40

(d) 50

Answer 1

Correct option is (d) 50

C₂H₂ + \(\frac 52\)O₂ → 2CO₂ + H₂O

4l of C₂H₂ requires = \(\frac{5 \times 4}{2}\) = 10 l of O₂

The volume of air required = \(\frac{100 \times 10}{20} = 50 l\)