In the reaction

$CaO+H_{2}O\to Ca{\left(OH\right)}_2+Heatenergy$

Calcium Water Calcium

oxide hydroxide

the possible state of Ca(OH)₂ is

1. liquid

2. aqueous

3. gaseous

4. solid

The correct option is B

aqueous

Combination reactions

Reactions in which bonds are formed such that a single product is formed by the reaction of two or more reactants are called combination reactions. These reactions release energy due to the formation of new bonds. These reactions are called synthesis reactions as a complex product is produced from simpler reactants.

Synthesis of slaked lime

The reaction of Calcium oxide (CaO) with Water (H₂O) produces slaked lime which is chemically Calcium hydroxide [Ca(OH)₂]. The reaction is an example of a combination reaction producing heat.

The chemical equation for the reaction is:

$CaO\left(s\right)+H_{2}O\left(l\right)\to Ca{\left(OH\right)}_2\left(aq\right)$

(Calcium (Water) (Calcium

oxide) hydroxide)

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(A) Calcium hydroxide is a solid and therefore is not obtained in pure liquid form. Option (A) is incorrect.

(C) Calcium hydroxide is not a gaseous substance and the heat cannot sublime it. Therefore, option (C) is incorrect.

(D) The Product formed is a solid. But due to the heat of the reaction, it is not obtained in solid state. Therefore, option (D) is incorrect.

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(B) The heat produced in the reaction causes the dissolution of the solid product in Water. Therefore, the slaked lime is obtained as an aqueous solution.

Therefore, the correct option is (B) aqueous