Question

Example of photochemical reaction is:
A. Formation of slaked lime
B. Decomposition of water
C. Mixing of acids and alkalis
D. Photosynthesis of HCI

Answer 1

Hint: The photochemical reaction is nothing other than a chemical reaction that begins with light being absorbed as a source of energy. Temporary peak states would be activated as the molecules absorb light and there would be physical and chemical property variations to a large degree from the actual molecules.

Complete answer:
Some reactions take place only in light and do not take place in dark e.g. photosynthesis in green plants or reaction between ${H_{\text{2}}}$ ​ and $C{l_{\text{2}}}$ to form HCl.

Reaction:
${H_2} + C{l_2} \to 2HCl$
In photosynthesis, light energy is captured by the chlorophyll present in the thylakoids of the chloroplast in order to produce photons to facilitate the conversion of water and carbon dioxide into sucrose or starch.

Hence, Option D is the right answer.

Note: HCl stands for Hydrogen Chloride. It was first prepared in the year 1648 by Glauber by heating sodium chloride with concentrated $H_2SO_4$. In the year 1840, Davy demonstrated that HCl is a complex of chlorine and hydrogen. The specific name for hydrochloric acid is muriatic acid.
Properties of Hydrogen Chloride are:
- HCl is an uncoloured gas which has a pungent scent.
- Hydrochloric acid is the aqueous solution of hydrogen chloride.
- HCl is soluble in water.
- It liquefies at 189 K to form a colourless liquid and freezes at 159k to form a white solid.