Zn and HCl are the reactants so our first order of business is to determine which is the limiting reactant based on the given equation Zn + 2 HCl −→ ZnCl2 + H2
1.6 mol Zn x (2 mol HCl / 1 mol Zn) = 3.2 mol HCl is the max that can be used in this situation, which means that HCl is in excess and Zn is the limiting reactant
The final step then is to convert from moles of Zn to moles of H2 using the 1:1 coefficient ratio
1.6 mol Zn x 1 mol H2 / 1 mol Zn = 1.6 mol H2
Hopefully that helps! Feel free to shoot me a message if you have any more questions beyond that :)
