(i) B to TI. The common oxidation states are +1 and +3 and +3. the stability of
+3 oxidation state decreases from B to TI.
+1 oxidation state increases from B to TI.
(ii) C to Pb. The common oxidation states are +4 and +2 the stability of
+4 oxidation state decreases from C to Pb ltbr. +2 oxidation state increases from C to Pb.