Answer:
[tex]\boxed{1.2 \times 10^{23}\text{ atoms}}[/tex]
Explanation:
6.023 × 10²³ atoms of Ca are in 1 mol of Ca
[tex]\text{No. of atoms} = \text{0.2 mol} \times \dfrac{6.023 \times 10^{23}\text{atoms }}{\text{1 mol }} = \mathbf{1.2 \times 10^{23}} \textbf{ atoms}}\\\\\text{There are }\boxed{\mathbf{1.2 \times 10^{23}} \textbf{ atoms}} \text{ atoms in 0.20 mol of Ca}[/tex]