First calculate number of Nitrogen atoms contained by 1 mole of Zn(NO₃)₂,
As one formula unit of Zn(NO₃)₂ contains 2 Nitrogen atoms, then one mole of Zn(NO₃)₂ will contain,
= 2 × 6.022 × 10²³
= 1.20 × 10²⁴ Atoms of Nitrogen / mole
Now, calculate number of Nitrogen Atoms in 0.150 moles of Zn(NO₃)₂.
As,
1 mole of Zn(NO₃)₂ contained = 1.20 × 10²⁴ atoms of N
Then,
0.15 mole of Zn(NO₃)₂ will contain = X atoms of N
Solving for X,
X = (0.15 mol × 1.20 × 10²⁴ atom) ÷ 1 mol
X = 1.80 × 10²⁴ Atoms of Nitrogen
Result:
So, 0.15 mole of Zn(NO₃)₂ contains 1.80 × 10²⁴ atoms of Nitrogen.
