Practical chemistry - practice paper

Practical chemistry - practice paper

a) Distinguish the following pairs of compounds using a common reagent.                               

i) Ethane and Ethene

ii) Ferric sulphate and Ferrous sulphate

iii) Sodium carbonate and Sodium sulphite

iv) MnO₂ and CuO

v) Na₂SO₄ and NaCl

vi) ZnCO₃ and CuCO₃

b) Identify A,B,C,D and E based on the following descriptions.                                               

i) When a compound X is heated with Conc. HCl gives a gas ‘A’ which turns starch iodide paper to blue black.

ii) A substance ‘P’ on heating  gives a colourless gas ‘B’ which turns alkaline Pyrogallol to dark brown.

iii) ‘Q’ is a compound which when reacts with a dil acid gives a gas ‘C’ has rotten egg smell.

iv) A compound contains an anion ‘D’ when treated with dil. acid gives a gas which turns lime water milky and has no effect on acidified Potassium dichromate.

v) A compound containing cation ‘E’ turns Nessler’s reagent dark brown.

c) Name the cations present in the following compounds if the following observations are seen when they are treated with Ammonium hydroxide.                                                                                           

i) A pale blue precipitate which dissolves in excess Ammonium hydroxide.

ii) A white ppt. which is insoluble in excess Ammonium hydroxide.

iii) A gelatinous white precipitate dissolves in excess Ammonium hydroxide.