Question 1

Which of the following elements is not a transition element?

Accepted Answer

Zinc (Zn) has a completely filled d-orbitals ($3d^{10}4s^2$) in its ground state as well as in its common oxidation state ($Zn^{2+}$). According to the definition, transition elements are those which have incompletely filled d-orbitals in their ground state or in any of their oxidation states. There

Question 2

The general electronic configuration of d-block elements is:

Accepted Answer

The general electronic configuration of d-block transition elements is represented as $(n-1)d^{1-10}ns^{1-2}$, where 'n' represents the outermost shell. The electrons are filled in the $(n-1)d$ orbitals after the completion of the ns orbital.

Question 3

Which transition metal exhibits the maximum number of oxidation states?

Accepted Answer

Manganese (Mn), belonging to the 3d series with the electronic configuration $3d^54s^2$, exhibits the maximum number of oxidation states ranging from +2 to +7. This is due to the participation of both 4s and 3d electrons in bonding.

Question 4

The colour of transition metal ions is generally due to:

Accepted Answer

The colour of transition metal ions is attributed to d-d electronic transition, where an electron from a lower energy d-orbital absorbs visible light and gets excited to a higher energy d-orbital within the same d-subshell.

Question 5

Which of the following ions is colored in aqueous solution?

Accepted Answer

An ion is colored if it has unpaired d-electrons. $Sc^{3+}$ has $3d^0$ (colorless), $Zn^{2+}$ has $3d^{10}$ (colorless), $Ti^{4+}$ has $3d^0$ (colorless), whereas $Ti^{3+}$ has $3d^1$ (one unpaired electron), making it colored.

The d-and f-Block Elements — CBSE Class 12 Chemistry Important Questions & Revision Notes