Class 10 Science chapter - 1 Chemical equations and reaction part -II

Q.1.Why should a magnesium ribbon be cleaned before burning in air?
Q.2  Write the balanced equation 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
Q.3.Write a balanced chemical equation 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.

Q.4  A solution of a 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.
Q.5  Why is the amount of gas collected in one of the test tubes in Activity 1.7(hydrolysis of water) double of the amount collected in the other? Name this gas.
Q.6  Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Q.7  Identify the substances that are oxidised and the substances that are reduced in the following reactions.
       (i) 4Na(S)+O2(g)→2Na2O(S)
       (ii) CuO(S)+H2(g)→Cu(S)+H2O(l)