AB + energy→ A +B 23.
The general equation shown is a reaction that is an

a. exothermic decomposition
b. endothermic decomposition
c. endothermic synthesis
d. exothermic synthesis

b. endothermic decomposition

Explanation:

Decomposition reaction:

It is the reaction in which one reactant is break down into two or more product.

AB → A + B

Synthesis reaction:

It is the reaction in which two or more simple substance react to give one or more complex product.

A + B      →      AB

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C +  H₂O  + 131 kj/mol  →  CO  + H₂

Thus, in given reaction energy is added and AB compound is decomposed to give A and B so this reaction is endothermic decomposition.