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2.8 × 10 –3 mol of CO 2 is left after removing 10 21 molecules from its 'x' mg sample. The mass of CO 2 taken initially is Given : N A = 6.02 × 10 23 mol –1

1. 196.2 mg
2. 98.3 mg
3. 150.4 mg
4. 48.2 mg

Correct answer: 196.2 mg

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