The number of atoms present in 4.25 grams of NH3 is approximately
6.02 X 1023
Number of atoms in a NH3 molecule is 4.
Atomic weight of Nitrogen is 14.
Atomic weight of hydrogen is 1.
Molecular weight of NH3 is
14+3(1)=17
So, no of atoms in the molecule is
4.2517 × 4 × 6.023 × 1023 = 6.023 × 1023