Qualitative Analysis of Cations - exam practice

Which of the following is a correct statement about the test for Fe²⁺ ions in solution?

Aqueous Cr³⁺ ions are reacted with an excess of aqueous sodium hydroxide.

Which product is formed?

What is observed when concentrated hydrochloric acid is added to an aqueous solution of CuSO₄ until no further change occurs?

Which observation would confirm that ammonia gas is released when solid ammonium chloride is warmed with solid calcium hydroxide?

Compound T is a white crystalline solid.

When a sample of T was mixed with aqueous sodium hydroxide and heated, a pungent smelling gas was produced which turned damp red litmus paper blue. This same gas produced dense white smoke with hydrogen chloride gas.

Further testing of a solution of T with barium chloride solution produced a dense white precipitate which did not dissolve when dilute hydrochloric acid was added to the mixture.

What is the identity of compound T?