Test: Introduction to d-Block Elements - NEET MCQ

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.

The second series includes the elements yttrium (symbol Y, atomic number 39) to cadmium(symbol Cd, atomic number 48). 

ilver in the form of Ag⁺ is colourless. For transition metal ions to exhibit color, their metal ions must have incompletely filled (n-1)d orbitals.

Ag⁺ =4d¹⁰,5s⁰

Ag⁺ has completely filled d orbitals hence is colourless.

Zn²⁺ has completely filled d-orbitals and there are no vacant d-orbitals for the transition of electrons, hence it is colourless.

Till d⁵ unpaired electron are increasing so maximum bonding as unpaired electron take part in bonding. So melting point increases till d⁵ then start decreasing due to pairing which decreases metallic bond strength and thus melting point.

Zn, Cd & Hg because the d-orbital of these elements are completely filled. So, they don't show the characteristics of transition elements (i.e. the d-orbital of transition elements is incomplete.

The first ionization energy of the d-block elements are between s and p-block elements. Thus they are more electropositive than p-block elements and less electropositive than s-block elements.

Since the configuration of Fe³⁺ ion is (argon ) 3d⁵,which contains maximum number of unpaired electrons, hence more will be paramagnetic behavior.