Identify the redox reactions out of the following reactions and identify the oxidising and reducing agents in them. 

(i) 3HCl(aq) + HNO₃ (aq) → Cl₂ (g) + NOCl (g) + 2H₂O (l )

(ii) HgCl₂ (aq) + 2KI (aq) → HgI₂ (s) + 2KCl (aq)

(iii) Fe₂O₃ (s) + 3CO (g) →   2Fe (s) + 3CO₂ (g)

(iv) PCl₃ (l) + 3H₂O (l) → 3HCl (aq) + H₃ PO₃ (aq)

(v) 4NH₃ + 3O₂ (g) → 2N₂ (g) + 6H₂O (g)

How many of these compounds will undergo disproportionation on hydrolysis? CO?, NO?, Cl?, F?, ClO?, Cl?O?, N?O?, SO?, P?O??

40. Best reducing agent is:
(a) He              (b) Be           (c) Li            (d) Al

37. Which element is considered to have oxidation number of +3 in all its compounds?

(a) Be              (b) Li             (c) Al         (d) Sc

36. Oxidation number ofS in S₂O₈^-2 is

(a) -2           (b) -6           (c) +2          (d) +6

32. Assertion: Na⁺ ion has an oxidation number of +1, Mg²⁺ ion, +2, Fe³⁺ ion, +3, Cl^– ion, –1, O^2– ion, –2; and so on.

Reason: For ions composed of only one atom, the oxidation number is equal to the charge on the ion.