Caffeine has a molecular mass of 194. If it contains 28.9% by mass of nitrogen, number of atoms of nitrogen in one molecule of caffeine is:
Correct answer: A. 4
- A. 4
- B. 6
- C. 2
- D. 3
Explanation
The correct answer is 4, as the molecular formula for caffeine is C8H10N4O2. This means there are 4 nitrogen atoms in each molecule. The percentage composition of nitrogen (28.9%) corresponds to this number based on the molecular mass of 194. Other options such as 6, 2, or 3 nitrogen atoms would either increase or decrease the nitrogen percentage, not aligning with the given data.
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