MCQ
The number of molecules in $4.25 \,g$ of ammonia are
  • A
    $0.5 \times {10^{23}}$
  • $1.5 \times {10^{23}}$
  • C
    $3.5 \times {10^{23}}$
  • D
    $1.8 \times {10^{32}}$

Answer

Correct option: B.
$1.5 \times {10^{23}}$
b
(b) Molecular weight of $N{H_3}$ is $17$

According to the mole concept

$17\,gm$ $N{H_3}$ has molecules $ = 6.02 \times {10^{23}}$

$\therefore \,\,1\,gm$ $N{H_3}$ has molecules $ = \frac{{6.02 \times {{10}^{23}}}}{{17}}$

$\therefore $ $4.25\,gm$ $N{H_3}$ has molecules $ = \frac{{6.02 \times {{10}^{23}} \times 4.25}}{{17}} = 1.5 \times {10^{23}}\,molecule$

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