Balance the following equations by the oxidation number method

(i) Fe²⁺ + H⁺ + Cr₂^2–O₇ → Cr₃⁺ + Fe₃⁺ + H₂O

(ii) I₂ + NO₃^–  → NO₂ + IO₃ ^–

(iii) I ₂ + S₂O₃^2–  → I^– + S₄O₆^2–

^{(iv) MnO₂ + C₂ O₄2– → Mn₂+ + CO₂}

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.