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.

AcademicChemistryNCERTClass 10

Element A is calcium (Ca) which reacts with water to give B calcium hydroxide [Ca(OH)2]. The reaction is written as:
$Ca+2H_2O →Ca(OH)_2+ H_2$

Calcium hydroxide [Ca(OH)2] on heating loses water to form C which is Calcium Oxide (CaO).
The reaction is written as:
$Ca(OH)_2 →CaO+H_2O$
Updated on 10-Oct-2022 13:27:26