Some Basic Concepts of Chemistry 1 Question 17
38. The total number of electrons present in $18 \mathrm{~mL}$ of water is
(1980, 1M)
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Solution:
- Considering density of water to be $1.0 \mathrm{~g} / \mathrm{mL}, 18 \mathrm{~mL}$ of water is $18 \mathrm{~g}(1.0 \mathrm{~mol})$ of water and it contain Avogadro number of molecules. Also one molecule of water contain
$2 \times($ one from each $\mathrm{H}$-atom $)+8 \times($ from oxygen atom $)$
$$ =10 \text { electrons. } $$
$\Rightarrow 1.0$ mole of $\mathrm{H}_{2} \mathrm{O}$ contain $=10 \times 6.023 \times 10^{23}$
$$ =6.023 \times 10^{24} \text { electrons. } $$
