1. (a) Metal X = Iron (Fe). (b) X will displace Cu from CuSO$_4$ because Fe
is more reactive than Cu.
$Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)$
(c) X will NOT displace Zn from ZnSO$_4$ because Fe is less reactive than Zn.
2. Ionic Compounds have high melting points because they have strong
electrostatic forces of attraction between oppositely charged ions. A lot of energy is needed to break these
bonds.
3. Assertion (A): Gold is found in free state in nature.
Reason (R): Gold is least reactive.
Both A and R are True. R is the correct explanation of A.
4. Anodising: Process of forming a thick protective oxide
layer on Aluminium by electrolysis. Al acts as the anode, and the natural oxide layer is made thicker,
offering better corrosion resistance. The layer can be dyed for decoration.
5. Food cans are coated with Tin (not Zinc) because Tin is less reactive than
Zinc and does not react with organic acids in food. Zinc would react and could be harmful.
6. Thermite Reaction:
$Fe_2O_3(s) + 2Al(s) \xrightarrow{\Delta} 2Fe(l) + Al_2O_3(s) + Heat$
7. This reaction is used for welding broken railway tracks or cracked machine
parts.
8. It is a Displacement Reaction. Aluminium, being more reactive, displaces
Iron from its oxide.
9. The reaction is highly exothermic. The heat generated is so intense
(~2500°C) that Iron is produced in molten form.
10. Impure metal is made the Anode. Pure metal
strip is made the Cathode. Electrolyte is a solution of the metal salt (e.g.,
CuSO$_4$ for Copper).
11. At Anode: Impure metal dissolves as ions ($Cu \rightarrow Cu^{2+} +
2e^-$). At Cathode: Pure metal is deposited ($Cu^{2+} + 2e^- \rightarrow Cu$).
12. Insoluble impurities (like gold, silver) settle at the bottom of the
anode as Anode Mud, which is collected.
13. Carbonate and Sulphide ores cannot be reduced directly with Carbon
because they are not stable under high temperatures. They first need to be converted to oxides by Roasting
(Sulphide) or Calcination (Carbonate).
14. When a metal reacts with a base, it releases Hydrogen gas (if it is
Amphoteric, like Zinc or Aluminium).
$Zn(s) + 2NaOH(aq) \rightarrow Na_2ZnO_2(aq) + H_2(g)$
