Answer:
317 g
Step-by-step explanation:
Cu + 2HCl --> CuCl2 +H2 
1 : 2 1 : 1 
1 mole of Cu = 63.5 g
1 mole of H2 = 2g 
1 mole Cu produces = 1 mole of H2 
63.5 g of Cu produces = 2 g of H2 
So 
10 g of H2 will be produced from = (63.5/2)*10 = 317 g of Copper