Attempt either option (A) or (B) : (A) (i) Give reasons for the following : (I) Ionic compound have…
Attempt either option (A) or (B) :
(A) (i) Give reasons for the following :
(I) Ionic compound have generally high melting points and boiling points.
(II) Solder, an alloy of lead and tin, is used for welding electrical wires.
(III) Carbon cannot reduce the oxides of Na or Mg.
(ii) The reaction of compound 'X' with aluminium is used to join railway tracks :
(I) Identify the compound 'X'.
(II) Name the reaction.
(III) Write the balanced chemical equation of the reaction of compound 'X' with aluminium. [3+2]
Solution
(A)
(i) (I) A considerable amount of energy is required to break
strong inter-ionic attraction.
(II) Solder has low melting point.
(III) Because Na or Mg have more affinity for oxygen
than carbon.
(ii) (I) Fe2 O3 / Iron (III) oxide
(II) Thermit reaction
(III) Fe2 O3 (s) + 2Al(s) → 2Fe(l) + Al2 O3 (s) + Ηeat
(Deduct ½ mark if no/ incorrect balancing)
OR
(B) (i)
(I) 2Cu2 O + Cu2 S → 6Cu(s) + SΟ2 (g)
(II) 2ZnS(s) + 3Ο2 (g) → 2ΖnΟ(s) + 2SΟ2 (g)
(Deduct ½ mark if no/ incorrect balancing)
(ii) (I) PVC provides insulation on the current carrying wires.
(II) Copper does not react with cold water, hot water and
steam. / Copper is a better conductor than steel.
(iii)
SECTION – C
PHYSICS