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.

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

(i) Sodium sulphite.

(ii) Iron [II] sulphide.

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.

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