Multiple choice

A gas mixture contains O2 and N2 in the ratio of 1 : 4 by weight. The ratio of their number of molecules is

  1. 1 : 8

  2. 1 : 4

  3. 3 : 16

  4. 7 : 32
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D Correct answer
Explanation

Ratio by weight: O2/N2 = 1/4. Molar masses: O2 = 32, N2 = 28. Ratio of molecules = (mass_O2/32) / (mass_N2/28) = (1/32) / (4/28) = (1/32) * (28/4) = 28/128 = 7/32.

AI explanation

Let the masses of oxygen and nitrogen be 1 g and 4 g, respectively. Their number of moles are 1/32 and 4/28, which simplifies to 1/32 and 1/7. The ratio of their molecules is the same as the ratio of their moles, so we calculate 1/32 divided by 1/7 to get 7/32, resulting in a ratio of 7 : 32.

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