MCQ
Caffeine has a molecular weight of $194$. If it contains $28.9\%$ by mass of nitrogen, number of atoms of nitrogen in one molecule of caffeine is
- ✓$4$
- B$6$
- C$2$
- D$3$
✓
Answer
Correct option: A.
$4$
a
(a) $100\,gm$ caffeine has $28.9\,gm$ nitrogen
(a) $100\,gm$ caffeine has $28.9\,gm$ nitrogen
$194\,gm$ caffeine has = $\frac{{28.9}}{{100}} \times 194 = 56.06\,gm$
$\therefore $ No. of atoms in caffeine $ = \frac{{56.06}}{{14}} \approx 4$.
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