Identify : An alkaline gas which produces dense white fumes when reacted with HCl gas.

Fill in the blank from the choices given in bracket : Ammonia gas is collected by ………….. (upward displacement of air, downward displacement of water, downward displacement of air)

Distinguish between the following pairs of compounds using the test given in bracket :

(i) Iron [II] sulphate and iron [III] sulphate [using ammonium hydroxide]

(ii) A lead salt and a zinc salt [using excess ammonium hydroxide]

State your observation : Calcium hydroxide is heated with ammonium chloride crystals.