Answer:
The reaction mentioned in the question is a decomposition reaction.
Step-by-step explanation:
Decomposition reaction is a specific type of chemical reaction in which the reactant molecule undergo break down to generate its respective products.
NaCl ⇒ Na + Cl2
In the above reaction sodium chloride(NaCl) undergo decomposition or break down to generate Sodium(Na) and chlorine gas(Cl2).