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The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1: 4. The ratio of number of their molecules is:

1. 1: 4
2. 7: 32
3. 1: 8
4. 3: 16

Correct answer: 7: 32

Solution

For mass ratio O:N = 1:4, moles of O2 = 1/32 and moles of N2 = 4/28 = 1/7. The molecule ratio = (1/32):(1/7) = 7:32.

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