A Solution of a Substance X is Used for White Washing (1) Name the Substance X and Write its Formula (2) Write the Reaction of the Substance X named in (1) Above with Water

Answer: 

1. The substance X is the chemical compound called calcium oxide. It is called quicklime or burnt lime. The formula for calcium oxide is CaO.

Characteristics of Calcium oxide:

• White or gray-white solid substance

• Odorless

• Occurs in the form of hard lumps

• Cubic hygroscopic crystals

2. The reaction of calcium oxide (substance X) with water is written as follows:

CaO (s) + H₂O (l) ⇌ Ca(OH)₂ (aq)

Calcium Hydroxide is called slaked lime. The reaction is accompanied by production of enormous heat (thermal energy) by formation of hydrate Ca(OH)₂  

The reaction is exothermic in nature.