The percentage yield if 4.65 g of copper is produced will be 70.4 %.
Step-by-step explanation:
The balanced equation is given as
2Al + 3CuSO4 ----> Al2(SO4)3 + 3Cu
1.87 g of Al = 0.0693 moles of Al * 3 moles of Cu / 2 moles of Al
= 0.10396 moles of Cu.
This corresponds to 6.606 g of Cu which refers to theoretical yield.
% yield = (actual / theoretical) * 100
= (4.65 / 6.606) * 100
% yield = 70.4 %.