The number of moles,n, may be calculates as the mass in grams divided by the molar mass
n = mass / molar mass
The molar mass is calculated adding the masses of all the elements in the molecular formula.
In this case
Element Number of atoms(N) atomic mass (am) N*am
Zn 1 65.4 g/mol 65.4 g
N 1*2 = 2 14.0 g/mol 2*14.0 = 28.0 g
O 3*2 = 6 16.0 g/mol 6*16.0 = 96.0 g
Molar mass = total = 65.4 g/mol + 28.0 g/mol + 96.0 g/mol = 189.4 g/mol
n = mass / molar mass = 151.50 g / 189.4 g/mol = 0.80 moles
