If 30 mL of H₂ and 20 mL of O₂ reacts to form water. what is left at the end of the reaction?

Options

(a) 10 mL of H₂
(b) 5 mL of H₂
(c) 10 mL of O₂
(d) 5 mL of O₂

Correct Answer:

5 mL of O₂

Explanation:

2H₂ + O₂ → 2H₂O
2 mol 1 mol 2 mol
2 vol 1 vol 2 vol
30 mL 15 mL 30 mL
Therefore, oxygen is in excess and amount of oxygen left
=20- 15= 5 mL