Chemistry Class 10 Chapter 14 Important MCQs 10th Chemistry Federal Board Chapter 14 The Atmosphere Fbise 1. Dry air consists of __ % Oxygen by volume. A.78 B.21 C.4 D.0.05 ANSWER: B (21%) 2. The % of Hydrogen in dry air is __. A.0.00005 B.0.70 C.0.98 D.1.7 ANSWER: A (0.0005%) 3. The air may containChemistry Class 10 Chapter 14 Important MCQs Federal Board