Question

“Action of water on quicklime” is an example of:
(A) Combination reaction
(B) Dissociation reaction
(C) Displacement reaction
(D) Double displacement reaction

Answer 1

Hint: Double displacement reaction is defined as when one component of each reactant gets displaced in the reaction. Displacement reaction can be defined as when one element or compound replaces another element or compound in the reaction. When a compound breaks into two or more components then this reaction is known as dissociation reaction. The complete detailed solution of the question is given in the below section:

Complete answer:
“Action of water on quicklime” is an example of combination reaction. Therefore, option A is the correct option. The reaction is given below.
 $ CaO + {H_2}O \to Ca{\left( {OH} \right)_2} + Heat $
The formula of quicklime is $ CaO $ . Its other name is calcium oxide. When calcium oxide reacts with water, it forms calcium hydroxide $ \left( {Ca{{\left( {OH} \right)}_2}} \right) $ . As you can clearly see in the above reaction that some heat is also released in the reaction. Therefore, this reaction is an exothermic reaction. This heat is even high as it can cause water to boil. The other name of calcium hydroxide is slaked lime. Calcium oxide is also known as metallic oxide. Slaked lime or calcium hydroxide is slightly soluble in water. Therefore, it forms a suspension in water.

Note:
When two or more substances combine with each other to form a single product, then this reaction is known as a combination reaction. The example has already been shown above. After suspension the clear solution is obtained and this solution gets settled down and therefore is known as lime water. We should take care of this reaction as it can cause damage to our eyes and skin. It means we should not put quicklime in water.