Answer the following question:
An element \(A\) reacts with water to form a compound \(B\) which is used in whitewashing. The compound \(B\) on heating forms an oxide \(C\) which on treatment with water gives back \(B\). Identify \(A\), \(B\) and \(C\) and give the reactions involved.
i. The element \(A\) is .
ii. The compound \(B\) is and the reaction when the element A reacts with water is .
iii. The compound \(C\) is and the reaction on heating the compound B is .
iv. The reaction of compound \(C\) with water is .