How many molecules, and how many atoms, are there in 44.1 g of sulphuric acid, H₂SO₄? …

Step 1. Molar mass. $2 \times 1\ \text{g/mol} + 32\ \text{g/mol} + 4 \times 16\ \text{g/mol} = 98\ \text{g/mol}$.

Step 2. Moles. $\dfrac{44.1\ \text{g}}{98\ \text{g/mol}} = 0.45\ \text{mol}$.

Step 3. Molecules. $0.45 \times 6.022 \times 10^{23} = 2.71 \times 10^{23}$.

Step 4. Atoms. $7 \times 2.710 \times 10^{23} = 1.90 \times 10^{24}$.