Question

A solution of a substance ‘X’ is used for white washing.

(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above with water.
Answer:
(i) The substance whose solution in water is used for white washing is calcium oxide (or quick lime). Its formula is CaO.​

Answer 1

i)

• The Substance whose solution is used for white washing is Calcium Oxide , commonly called as quick lime.
• It's chemical formula is CaO with a molecular mass of 56.08u.

ii)

• When Calcium Oxide reacts with water , it forms Calcium hydroxide and releases heat and therefore,the reaction becomes an exothermic combination reaction.
• 
  `CaO + H_2O \rightarrow \: Ca(OH)_2 + heat \\`