Q1 of 28 Page 6

Why should a magnesium ribbon be cleaned before burning in air?

Magnesium ribbon has a protective layer of magnesium carbonate on its surface. It should be cleaned by sand paper before burning in air so that it may readily combine with the oxygen of air on heating.


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2

Write the balanced equations for the following chemical reactions:

(i) Hydrogen + Chlorine → Hydrogen chloride


(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride


(iii) Sodium + Water → Sodium hydroxide + Hydrogen

 3

Write balanced chemical equations with state symbols for the following reactions:

(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.


(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

 1

A solution of substance X is used for white washing.

(i) Name the substance X and write its formula.


(ii) Write the reaction of the substance X named in (i) above with water.

 2

Why is double the amount of a gas collected in one of the test-tubes in the electrolysis of water activity? Name this gas.