Caffeine has a molecular weight of 194 u. If it contains 28.9 % by mass of nitrogen, number of atom of nitrogen in one molecule of caffeine is

Question

Caffeine has a molecular weight of 194 u. If it contains 28.9 % by mass of nitrogen, number of atom of nitrogen in one molecule of caffeine is (A) 4 (B) 6 (C) 2 (D) 3

Tardigrade Admin · Accepted Answer

Molecular weight of caffeine =194 u N present in one molecule of caffeine =28.9 % of 194 u =(28.9/100) × 194=56 u Mass of one N atom =14 m ∴ 14 u=1 N atom ∴ 56 u=(56/14) N atom =4 N atom

Q. Caffeine has a molecular weight of $194 u$ . If it contains $28.9%$ by mass of nitrogen, number of atom of nitrogen in one molecule of caffeine is

4

6

2

3

Molecular weight of caffeine $= 194 u$ N
present in one molecule of caffeine $= 28.9%$ of
$194 u = \frac{28.9}{100} \times 194 = 56 u$
Mass of one $N$ atom $= 14 m$
$∴$ $14 u = 1 N$ atom
$∴ 56 u = \frac{56}{14} N$ atom $= 4 N$ atom

Q. Caffeine has a molecular weight of 194u. If it contains 28.9% by mass of nitrogen, number of atom of nitrogen in one molecule of caffeine is

4

6

2

3

Molecular weight of caffeine =194u N present in one molecule of caffeine =28.9% of 194u=10028.9​×194=56u Mass of one N atom =14m ∴ 14u=1N atom ∴56u=1456​N atom =4N atom

Q. Caffeine has a molecular weight of $194 u$ . If it contains $28.9%$ by mass of nitrogen, number of atom of nitrogen in one molecule of caffeine is

Molecular weight of caffeine $= 194 u$ N
present in one molecule of caffeine $= 28.9%$ of
$194 u = \frac{28.9}{100} \times 194 = 56 u$
Mass of one $N$ atom $= 14 m$
$∴$ $14 u = 1 N$ atom
$∴ 56 u = \frac{56}{14} N$ atom $= 4 N$ atom