Question

(a) What is meant by disproportionation of an oxidation state ? Give one example.
(b) Draw the structures of Cr₂O₇ 2^-, CrO₄ ^-2, MnO_4^-.
(c) What is the effect of lanthoids contraction beyond lanthanoid ?

Answer 1

When any atom or ion undergo oxidation and reduction simultaneously it is called disproportionation.
2Cu+→  Cu+2 + Cu

(c) Size of respective 4d and 5d series elements becomes comparable from
fourth group onwards (e.g., Zr and Hf)