`Mg^(+2)` ion is smaller than `O^(-2)`ion in size though both are iso electronic -Explain.

A crystal of lead (Ii) sulphide has fcc structure. In this crystal the shortest distance between a Pb^(2+) ion and a S^(2-) ion is 297pm. What is the length of the unit cell is lead sulphide? Also Calculate the unit cell volume (N_A=6.023xx10^23 mol^-1, Pb=297.2u, S=42 u)

What will be the correct order for the wave lengths of absorption in the visible region for the following. Explain the fact. [Ni(NO_2)_6]^+, [Ni(H_2O)_6]^(2+)

Why Sm^(2+) , Eu^(2+) and Yb^(2+) ions in solutions are good reducing agents but an aqueous solution of Ce^(4+) is a good oxidising agent?

Show the formation of Aluminium oxide ( Al_2O_3 ) by the transfer of electrons.

Non-Stoichiometric cuprous oxide, Cu_2O can be prepared in laboratory. In this oxide, copper to oxygen ratio is slightly less than 2:1. Can you account for the fact that this substance is a p-type semiconductor?