The correct option is
D Exothermic reaction
The correct option is option D
The explanation for the correct option:
- An exothermic reaction is a chemical process that is characterized by the release of energy in the form of heat or light.
- When bonds are broken, less energy is lost than that is released when new ones are formed. That's why heat is produced to release the extra energy.
- The energy released by the reaction is greater than the activation energy required to start it.
- The energy lost is released into the environment. As a result, the change in enthalpy (a quantity that measures a system's heat content by calculating the change in energy) is negative in such a process.
- Example: Formation of ammonia
The explanation for the incorrect option:
Option (A): Endothermic reaction
- Any chemical process that takes heat from its surroundings is said to be endothermic. The reaction's activation energy comes from the energy that was absorbed.
- Hence, it is an incorrect option.
Option (B): Displacement reaction
- A chemical reaction in which one element in a compound is replaced by another is referred to as a single-displacement reaction. This reaction is also referred to as a single replacement reaction or exchange reaction.
- They are a type of exothermic reaction.
- Hence, it is an incorrect option
Option (C): Combination reaction
- A combination reaction is one in which two or more reactants combine to create a single result.
- They can or cannot be exothermic
- Hence, it is an incorrect option.
Final answer: Heat is evolved during exothermic reactions.