Give an example of a reaction that requires light.
Photodecomposition reaction:
Decomposition of Silver chloride:-
2AgCl(s)Silverchloride→light2Ag(s)Silver+Cl2(g)Chlorinegas
Therefore, an example of a reaction that requires light is the decomposition of silver chloride (AgCl) in presence of light:
Give an example of a reaction where the following are involved:
(a) Evolution of heat
(b) Absorption of heat
(c) High pressure is required