Pick out the correct statements from the following.
(I) Cobalt (III) is more stable in octahedral complexes.
(II) Zinc froms coloured ion or complexes.
(III) Most of the d-block elements and their compounds are ferromagnetic.
(IV) Osmium show (VIII) oxidation sate.

Options

A. I and II
B. I and III
C. II and IV
D. I and IV

Answer

D

Explanation

(I) `Co^(3+)` have higher charge density than `Co^(2+), So Co^(3+)` is more stable in octahedral complexes.
(II) Zn exhibits only `+2` oxidation state.So, `Zn^(2+)=[Ar]3d^(10),4s^(0)`
Since, iy does not contain any unpaired electron, its compounds are colourless.
(III) d-block elements are generally paramagnetic and sometime diamagnetic , but not ferromagnetic.
(IV) Osmium and ruthenium are VIII group elements, so can exibit the highest oxidation state`+8` in their oxides,
Hence, statements I and IV are correct.