UPPCS · Question 108
Which of the following gases is/are lighter than air? 1. Hydrogen chloride 2. Sulfur dioxide 3. Helium Select the correct answer using the code given below.
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Answer: (A) Only 3
Explanation
Air's average molar mass is about 29 g/mol. Helium (4) is lighter; HCl (36.5) and SO2 (64) are heavier.