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

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

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.

Dinitrogen and dioxygen are main constituents of air, but these do not react with each other to form oxides of nitrogen because _________. 
(i) The reaction is endothermic and requires very high temperatures. 
(ii) The reaction can be initiated only in presence of a catalyst. 
(iii) Oxides of nitrogen are unstable. 
(iv) N₂ and O₂ are unreactive.