Answer:
56 L of HCl
Step-by-step explanation:
The equation for the reaction is;
H₂(g )+ Cl₂(g) →2HCl(g)
Volume of Chlorine gas = 28 L 
According to the question, 1 mole of a gas occupies 22.4 L at stp.
We are required to determine the volume of HCl produced.
Step 1: Moles of Chlorine gas that reacted 
Volume of Chlorine gas = 28 L
But;
1 mole = 22.4 L
Therefore;
Moles of Chlorine gas = 28 L ÷ 22.4 L 
 = 1.25 moles of Cl₂
Step 2: Number of moles of HCl 
From the equation 1 mole of Cl₂ reacts with hydrogen gas to produce 2 moles of HCl 
Therefore, the mole ratio of Cl₂ to HCl is 1: 2
Thus; moles of HCl = 1.25 × 2
 = 2.5 moles 
Step 3: Volume of HCl gas prdouced 
We know that. 1 mole of a gas = 22.4 L
Thus,
The volume of HCl = 2.5 moles × 22.4 L/mol 
 =56 L of HCl
Therefore, 56 L of HCl are produced when 28 L of chlorine gas reacts with excess hydrogen gas.