Question

A substance X when mixed with water is used for white washing. the substance x is also formed when a substance Y decomposes. identify X and Yams write their formula.

Answer 1

The substance X is CaO,calcium oxide.it reacts with water to form slaked lime Ca[OH]2

CaO + H2O - Ca[OH]2+ H2

Answer 2

Answer : X and Y are calcium oxide $(CaO)$ and calcium hydroxide $(Ca(OH)_2)$ respectively.

Explanation :

When calcium oxide (quick lime) mixed with water then it gives calcium hydroxide (slaked lime) as a product.

The balanced chemical reaction will be,

$CaO+H_2O\rightarrow Ca(OH)_2$

When calcium hydroxide decomposes then it gives calcium oxide and water as a product.

The balanced chemical reaction will be,

$Ca(OH)_2\overset{\Delta}\rightarrow CaO+H_2O$

So, we conclude that the substance X is calcium oxide and Y is calcium hydroxide and the formula of calcium oxide is CaO and calcium hydroxide is, $Ca(OH)_2$

Hence, X and Y are calcium oxide $(CaO)$ and calcium hydroxide $(Ca(OH)_2)$ respectively.