Answer:
1.28 x 10²³ silver atoms.
Explanation:
Using cross multiplication:
1.0 mole of silver → 6.022 x 10²³ silver atoms.
0.2124 mole of silver → ??? silver atoms.
∴ The no. of atoms of silver that are in 0.2124 moles of silver = (0.2124 mole)(6.022 x 10²³) / (1.0 mole) = 1.28 x 10²³ silver atoms.