how many liters (at STP) of chlorine gas are required to produce .050L of hydrogen chloride gas?

Answer 1

H2 + Cl2 ==> 2HCl

Since these are gases one may use L (volume) as if the volume were mols.
0.5 L HCl x (1 mol H2/2 mols HCl) = 0.5 x 1/2 = ?