Question

The total number of electrons in 18 ml of water (density $=1gm{l}^{-1})$ is :

• A. $6.02\times {10}^{23}$
• B. $6.02\times {10}^{25}$
• C. $6.02\times {10}^{24}$
• D. $6.02\times 18\times {10}^{23}$

Answer 1

Answer: (C)

$6.02\times {10}^{24}$

The total number of electrons in $18$ ml of water is $6.02\times {10}^{24}$. Since, the density is $1$ g/mL, $18$ ml of water corresponds to $18$ g or $1$ mole as the molecular weight of water is $18$ g/mole.

$1$ mole of water contains $10$ moles of electrons, $8$ moles of electrons from $O$ and $2$ moles of electrons from $H$.

$1$ mole of electrons corresponds to avogadro's number which is $6.02\times {10}^{23}$ $\times$ $10$ moles of electrons will correspond to $6.02\times {10}^{24}$ electrons.