Answer:
There are 8.55ₓ10²⁵ atoms of P, in 7.1 moles of Cu₃(PO₄)₂
Explanation:
Copper (II) ⇒ Cu²⁺
PO₄⁻³ → phosphate
3Cu²⁺ + 2PO₄⁻³ → Cu₃(PO₄)₂
1 mol of copper (II) phosphate has 2 mol of P, 8 moles of O and 3 moles of Cu.
Then, 7.10 moles of salt has (7.1 .2) = 14.2 moles of P
In 1 mol we find, NA atoms (6.02ₓ10²³)
In 14.2 moles we would find (14.2 .NA) = 8.55ₓ10²⁵ atoms
