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)

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

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]

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