Verified answer

CuO(s) + H2(g) -------> Cu(s) + H2O(l)

1 mole (79.55g) of CuO will be reduced by 1 mole (2.016g) of hydrogen gas.

Hence 7.95g of CuO is 0.10mole of CuO and this will require 0.10 mole of hydrogen = 0.2016g of hydrogen.

not sure if this is right but i think this is the ans :

h2+CuO----->H2O+Cu

no. of moles of CuO=mass/molecular mass

=7.95/79.5

=0.1moles of CuO present

no of moles of hydrogen = x(mass of H2)/2

=x/2

since they r in the ratio 1:1

therefore, 1 of h2------> 1 of cuo

x/2<------- 0.1of cuo

x=0.2 !!!= amt of h2 required !