(i)ZnO+C → Zn+CO

(ii) Impure zinc is electro-refined by using impure zinc as an anode, pure zinc as a cathode and an aqueous solution of ZnSO₄ as electrolyte containing a little H₂SO₄.
Cathode → Zn²⁺ + 2e^- → Zn
Anode → Zn → Zn²⁺ + 2e^‒

(i) Due to the presence of unpaired electrons in d-orbitals and empty d-orbitals. Gives rise to possibility of d-d transition.
(ii) X—Y bonds are weaker than X—X and Y—Y bonds/Polar nature of X—Y bonds/Less overlapping of orbitals in X—Y bond.
(iii) Cu¹⁺ has no unpaired electrons, hence diamagnetic. Cu²⁺ has unpaired electrons, hence paramagnetic. [Cu→29→1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 4s¹ , 3d¹⁰]
[Cu¹⁺→28→1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 3d¹⁰; d-orbital fully filled]
all electron in Cu¹⁺ is paired.
[Cu²⁺→27→1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 4s¹ , 3d⁹ ; d-orbital partially filled 1 unpaired electron].

Hydrolysis of ethyl acetate to give ethanol and acetic acid is catalyzed by dilute H₂SO₄.

The electronic configuration of Cr (24) is 1s², 2s²p⁶, 3s²p⁶d⁵,4s¹.
This is because an electronic configuration with half-filled and completely filled orbitals is more stable. Cr has 3d orbitals half filled configuration which is more stable than normally expected i.e 3d⁴ 4s².