First, find how many moles of H_2H2 gas will take up 104 liters.
(1 mol H_2(g))/(22.4L) = ("x" mol H_2(g))/(104L)1molH2(g)22.4L=xmolH2(g)104L
x = 4.642857143molsx=4.642857143mols
Now use the reaction coefficients to find the moles of hydrochloric acid needed to form the above moles of hydrogen gas.
mols HCl = 4.642857143molsH_2 * (2 mols HCl)/(1 mol H_2)molsHCl=4.642857143molsH2⋅2molsHCl1molH2
mols HCl = 9.285714286molsHCl=9.285714286
To find grams of HCl just multiply the moles of HCl by its molar mass.
grams HCl = 9.285714286mols HCl * 36.46094 g/(mol)gramsHCl=9.285714286molsHCl⋅36.46094gmol.
grams HCl = 338.565871439 gramsgramsHCl=338.565871439grams
Since you only have 3 sig figs, the answer would be:
grams HCl = 339 gramsgramsHCl=339grams