Answer: 1.75 mol of copper
Explanation: in the given balanced equation for the reaction of copper and silver nitrate, we can see that with one mol of copper, we can form two moles of silver (Ag), so we can calculate how many moles of copper we need to form 3.50 moles of Ag as follows:
3.50 moles of Ag *1 mol of copper/2 moles of Ag=
3.50mol of copper/2=
1.75 mol of copper