Fill in the blank : ……………[AgCl / PbCl₂], a white precipitate is soluble in excess NH₄OH.

State your observations when dilute hydrochloric acid is added to :

(i) Lead nitrate soln. and the mixture is heated.

(ii) Copper carbonate.

(iii) Sodium thiosulphate.

Select the correct answer from A, B, C and D : The aim of the Fountain experiment is to prove that :

(A) HCl turns blue litmus red

(B) HCl is denser than air

(C) HCl is highly soluble in water

(D) HCl fumes in moist air.

Identify the gas evolved and give the chemical test when dilute hydrochloric acid reacts with :

(i) Sodium sulphite.

(ii) Iron [II] sulphide.