Which of the following gasses is/are lighter than air? 1. Hydrogen chloride 2. Sulfur dioxide 3. Helium . Select the correct answer from the code given below : Code :

To determine if a gas is lighter than air, we need to compare its molecular weight with the average molecular weight of air. The average molecular weight of air is approximately 29 g/mol (about 80% N2, molecular weight 28 g/mol, and 20% O2, molecular weight 32 g/mol). 1. Hydrogen chloride g/mol. This is heavier than air. 2. Sulfur dioxide (SO2): Molecular weight = 32 (S) + 2 16 (O) = 64 g/mol. This is much heavier than air. 3. Helium (He): Atomic weight = approximately 4 g/mol. This is significantly lighter than air.