Select the correct statement about elements of group .
(A) The order of stability of oxidation state for +3 is and for +5 is
(B) In the case of nitrogen, all oxidation states from +1 to +4 tend to disproportionate in acid solution.
(C) There is considerable increase in covalent radius from N to P but from As to Bi only a small increase in covalent radius is observed.
(D) All of these.
(D) (A) This is due to the inert pair effect in the heavier p-block elements.
(C) This is due to the presence of completely filled d and l or f orbitals in heavier elements. Covalent radius l pm; N =70, P =110, As =120, Bi =150.