The balanced reaction of Hcl with oxygen gas will be
4HCl + O2 ---> 2H2O + 2Cl2(g)
Thus from balanced equation it is clear that four moles of HCl will give two moles of Cl2 gas
Or
For 2 moles of Cl2 gas we need four moles of HCl
Molar mass of HCl = 36.5 g / mole , four moles = 4 X 36.5 = 146g
Molar mass of Cl2 = 71g /mole
Hence
2 moles = 2 X 71 = 142 g
Therefore
for 142g of Cl2 we need 146g of Hcl
for one gram of Cl2 we need = 146 / 142g of HCl
For 335g of Cl2 we need = 146 X 335 / 142 = 344.4 g of HCl