Reaction involved is:

MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O

Assign the oxidation states we get:

O₂ + H → Cl₂ +

thus electron change in oxidation of Cl and reduction of Mn are same –2 electrons each

balance Cl

O₂ + 4H → Cl₂+

Balance O by adding H₂O

O₂ + 4H → Cl₂₊ + 2H₂O

∴  balanced chemical reaction is:

MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

The reaction can be represented in the ionic form as:

MnO₂ + 4Cl⁻ + 4H⁺ → Mn²⁺ + 2Cl⁻ + Cl₂ + 2H₂O

OR

MnO₂ + 2Cl⁻ + 4H⁺ → Mn²⁺ +Cl₂ + 2H₂O

is the correct representation of reaction occurring when HCl is heated with MnO₂