Question

A chemical reaction that takes place with the evolution of heat is an
A. reversible reaction
B. Endothermic reaction
C. Thermal reaction
D. Exothermic reaction
E. Irreversible reaction

Answer 1

For the chemical reactions to occur, the energy is either absorbed (on the reactant side) or released. Different names are given to different reactions according to their properties and the changes undergone by the reactants and products.

Complete answer:
The reactions with temporary changes, the products can be converted to reactants again are called reversible reactions whereas the reactions with permanent changes, the products cannot be converted to reactions again are called irreversible reactions.
$A + B \rightleftharpoons C + D$ is a representation of reversible and
$A \to C + D$ is a representation of irreversible reaction.
The reactions where energy (heat or light) is absorbed are called endothermic reactions whereas the reactions where energy (heat or light) is released are called endothermic reactions.
Reactant $\to$ Product + energy is a representation of endothermic and
Reactant + energy $\to$ Product is a representation of exothermic reaction
Thermal basically refers to the reactions involving the heat energy these can be both endothermic and exothermic.
Thus it can be seen that the heat (energy) is getting released during an exothermic reaction.
Those reactions in which the heat is absorbed are known as endothermic reactions.
Example: during combustion a lot of heat energy is absorbed and it is given as:
$C{H_4} + {O_2} \to C{O_2} + {H_2} + Heat$

Hence the correct option is D.

Note: An exothermic reaction occurs when the temperature of a system increases due to the evolution of heat which is then released into the surroundings.
We can also represent heat with the symbol $\Delta$.