Question

The total number of electrons present in $18$ ml of water (Density of water is $1kg{L}^{-1})$ are ?

• A. $6.02\times {10}^{23}$
• B. $6.02\times {10}^{22}$
• C. $6.02\times {10}^{24}$
• D. $6.02\times {10}^{25}$

Answer 1

Answer: (C)

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

To find the number of electrons, we have to first find the number of moles of water, as $1$ mole contains $6.023\times {10}^{23}$ atoms or molecules.
$Density=\frac{Mass}{Volume}$
$Mass=Density\times Volume$
Density $=1Kg/L$
Volume $=18ml=18\times {10}^{-3}L$
Mass $=1\times 18\times {10}^{-3}=18gm$
Molecular weight of water $=18$.
Number of moles of water $=\frac{18}{18}=1$
So, $1$ mole of water contain $6.023\times {10}^{23}$ molecules.
$1$ molecule of water contains $=10$ electrons
$6.023\times {10}^{23}$ molecule of water contain $=6.023\times {10}^{24}$ electrons