Question

Which is a reaction that absorbs energy?
A. Exothermic
B. Particle size
C. Endothermic
D. Catalyst
E. Concentration

Answer 1

An endothermic process is one in which the system's enthalpy $H$ (or internal energy $U$ ) increases. A closed system absorbs thermal energy from its surroundings, which is heat transfer into the system, in such a process. It could be a chemical process, like dissolving ammonium nitrate in water, or a physical process, like ice cube melting.

Complete Step By Step Answer:
An endothermic reaction is a chemical reaction that absorbs energy from the environment. An exothermic reaction is the polar opposite of an endothermic reaction. The products of reversible reactions can react to remake the original reactants. Heat energy is normally transported as the energy is absorbed by the process. A thermometer can occasionally be used to identify a temperature drop. Endothermic reactions include the following:
1. Photosynthesis
2. The reaction between ethanoic acid and sodium carbonate.
3. Dissolving ammonium chloride in water.
Hence, the correct option is: (C) Endothermic.

Additional Information:
To keep cool, the human body uses the endothermic characteristic of evaporation. Sweating serves as a means of accomplishing this. Sweat (formed on the skin's surface) absorbs heat from the skin and evaporates, resulting in a cooling effect.

Note:
It should be emphasized that an endothermic process is one that absorbs heat from its environment. As a result, all endothermic reactions and processes are endothermic in nature. This is not the case, however. Physical rather than chemical changes are prevalent in many endothermic reactions.