The correct options are
A Cl2+2⊖OH⟶Cl⊖+ClO⊖+H2O
B 2HCuCl2⟶Cu+Cu2++4Cl⊖+2H⊕
C HCHO+⊖OH⟶CH3OH+HCOO⊖
a. 2e−+Cl2⟶2Cl⊖ (Reduction)
2ClO⊖+2e− (Oxidation)
Hence, it is a disproportionation reaction.
b. It is also a disproportionation reaction.
[+1H+1Cu−1×2Cl2]
e−+Cu1+⟶Cu (Reduction)
Cu1+⟶Cu2++e− (Oxidation)
c. It is also a disproportionation reaction.
HCHO is oxidised to HCOO⊖ and reduced to CH3OH.
d. It is not, sinc,e the oxidation state of Mg is +2 in both reactant and product. Similarly, the oxidation states of C and O are +4 and -2 in both reactant and product.