question_answer

  Give reasons : (a) Rusting of iron pipe can be prevented by joining it with a piece of magnesium.                                            1 (b) Conductivity of an electrolyte solution decreases with the decrease in concentration.                             1

Answer:

                  (a) Rusting of iron is prevented in the given case due to cathodic protection in which magnesium metal is                 oxidised in presence to iron and acts as anode.                                                                                                                  1 (b) When the concentration decreases the number of ions present in unit volume of solution decreases as a result electrical conductivity decreases.                                                                                                                                             1