The number of electrons present in charge of 1 coulomb is : 

Charge on a given number of electrons can be given as:

Charge(Q) = Number of electrons(n) X Charge of an electron(e)
$\Rightarrow \mathrm{Q}=\mathrm{ne}\hspace{0.17em}$ 

We need to find the number of electrons present in a 1-coulomb charge.
$\therefore \mathrm{Q} = 1 \mathrm{C}$
$\therefore 1=\mathrm{ne}$

Charge on one electron is:
$\mathrm{e}= 1.6 \mathrm{X} {10}^{-19} \mathrm{C}$
$\Rightarrow \text{n}=\frac{1}{\mathrm{e}}=\frac{1}{1.6\times {10}^{-19}}$

$\mathrm{n}=\frac{1}{1.6}\times {10}^{19}=6.25\times {10}^{18}\mathrm{electrons}$

Therefore, the number of electrons in a charge of 1 coulomb will be  $6.25\times {10}^{18}$.