Answer;
= 9.45 × 10^23 molecules
Explanation;
The molar mass of Na2SO4 = 142.04 g/mol
Number of moles = mass/molar mass
= 223/142.04
= 1.57 moles
But;
1 mole = 6.02 × 10^23 molecules
Therefore;
1.57 moles = ?
= 1.57 × 6.02 × 10^23 molecules
= 9.45 × 10^23 molecules