Pick out the correct statements from the following
1. Cabalt (III) is more stable in octahedral complexes
2. Zinc forms coloured ions or complexes
3. Most of the d- block elements and their compounds are ferromagnetic
4. Osmium shown (VIII) oxidation state

Options

A. a) 1 and 2
B. b) 1 and 3
C. c) 2 and 4
D. d) 1 and 4

Answer

D

Explanation

1 `Co^(3+)` have higher charge density than `Co^(2+)`, so `Co^(3+)` is more stable in octahedral complexes .
2. Zn exhibits only +2 oxidation state .So
`Zn^(2+)=[Ar]3d^(10),4s^(0)`
Since it does not contain any unpaired electron , its compounds are colourles .
3. d- block elements are gennerally paramagnetic and sometimes , but not ferromagnetic
4. Osmium and rutheniumm are VIII group elements , so can exhibit the highest oxidationn state +8 in their oxides , eg `OsO_(4)` .
Hence , statement 1 and 4 are correct .