Question

Carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water.
${\text{Ca(OH}}{{\text{)}}_{\text{2}}}{\text{ + C}}{{\text{O}}_{\text{2}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
What is this reaction known as?
(A) Neutralisation
(B) Decomposition
(C) Double decomposition
(D) Thermal decomposition

Answer 1

In the above question, it is asked about which reaction is carried out when carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water. Here, the product formed is salt and water and hence, it is an example of reaction where salt and water are formed.

Complete step by step solution
In the above question, the options given are different types of reactions. Let us discuss them briefly.
Neutralisation:
A neutralization reaction is a reaction in which an acid and a base react to form water and a salt.
Decomposition:
A decomposition reaction is a reaction in which a compound breaks down into two or more simpler substances.
Double decomposition:
A double decomposition reaction is a reaction in which the positive ions and negative ions in two compounds switch partners to form two new compounds.
Thermal decomposition:
Thermal decomposition is the decomposition which is caused by heat.
We have the reaction given as:
${\text{Ca(OH}}{{\text{)}}_{\text{2}}}{\text{ + C}}{{\text{O}}_{\text{2}}} \to {\text{CaC}}{{\text{O}}_{\text{3}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
We can clearly see that since, the reaction given to us results in formation of salt and water. And hence, it is an example of neutralisation reaction.
So, the correct option is option A.

Note:
Neutralisation reaction helps in returning the pH levels to neutral level. Sometimes the soil becomes acidic and for the growth of plants, we need a neutral medium and hence, we can add some basic substance to make it neutral.