Test: Properties of D-block elements - JEE MCQ

Tendency of an element to form complexes does not depend on whether the element shows variable O.S. or not

Co⁺² = [Ar] 3d⁷
Cu²⁺ = [Ar] 3d⁹
Mn⁺² = [Ar] 3d⁵
Sc⁺³ = [Ar]
We can see that only Sc⁺³  has no unpaired electron, so it is a diamagnetic ion.

The inner transition elements are the elements in which the added electrons go to (n-2) f-orbitals. These include lanthanoids and actinoids. In lanthanoids, the added electron goes to 4f orbital and in actinoids, the added electron goes to 5f orbital.

Both of these ions have no unpaired electron, hence these are colourless.

Transition metals exhibit variable valency.

and have -shells completely filled hence they do not exhibit variable valency.

is diamagnetic as it does not contain any unpaired electron while others contain.

are coloured ions
hence the answer is .

Magnetic moment where number of unpaired electrons

In there is no unpaired electron, contains one unpaired electron hence coloured.