The number of molecules in $4.25$ g of $N{H}_3$ is :

The number of molecules present in $4.25grams$ of $N{H}_3$ is approximately:

THe number of molecules in 4.25 g of ammonia is:
(a) $1.0\times {10}^{23}$ (b) $1.5\times {10}^{23}$
(c) $2.0\times {10}^{23}$ (d) $3.5\times {10}^{23}$

The number of molecules in 16.0g of oxygen is