Q18 of 47 Page 1

Give reasons for the following:

(a) O-O single bond is weaker than S-S single bond.


(b) Tendency to show -3 oxidation state decreases from Nitogen(N) to Bismuth(Bi).


(c) Cl2 acts as a bleaching agent.


(a) O has smaller size than S due to which the O-O bond length is short which results in repulsion of lone pairs on O making it unstable and the bond can be cleaved. Whereas due to big size of S, no such repulsion is present and the S-S bond is stronger than that between O-O.


(b) Tendency to exhibit -3 oxidation state decreases down the group due to increase in size and metallic character.


(c) Chlorine water on standing loses its yellow colour due to the formation of HCl and HOCl. Hypochlorous acid (HOCl) so formed, gives nascent oxygen which is responsible for oxidising and bleaching properties of chlorine.


Cl2 + H2O HCl + HOCl


HOCl HCl + (O)


Coloured substance + (O) Colourless substance


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