Answer:
H2(g) + Cl2(g) → 2HCl(g)
Step-by-step explanation:
The equation should be
H2(g) + Cl2(g) → HCl(g)
All the constituents involve in the reaction are in it gaseous state(as indicated with this (g) symbol ). To balance the equation, the number of atom of elements on the reactant sides(left side) must be equal to that on the product(right side).
From the equation above the reactant side has 2 atom of hydrogen(H2) and 2 atom of chlorine(Cl2) but the number of hydrogen and chlorine atom found on the product side is 1 atom each(HCl) . so we need to balance the equation.
The balanced equation is as follow
H2(g) + Cl2(g) → 2HCl(g)