Question

Give 2 examples of each of following occuring during a chemical reaction.
(i) Change of state
(ii) change of colour
(iii) evolution of gas
(iv) Formation of precipitate​

Answer 1

Answer:

change of colour

formation of precipitate

Answer 2

(i) Change of state - sublimation and deposition

(ii) Change of colour - Rusting and blackening of surfaces of cut vegetables and fruits 

(iii) Evolution of gas - When zinc reacts with hydrochloric acid, hydrogen gas is evolved with formation of zinc chloride and When limestone and HCl react with each other, carbon dioxide gas is evolved.

(iv) Formation of precipitate - AgNO3(aqueous) + KCl(aqueous) —–AgCl(precipitate) + KNO3(aqueous) and 2KOH(aqueous) + CaCl2(aqueous)—-Ca(OH)2(aqueous) + 2KCl(aqueous)