Question

Differentiating electrons in inner transition elements enters the _______ orbital.
A.s
B.p
C.d
D.f

Answer 1

We know that the inner transition elements are those elements that belong to the f-block of the periodic table. They are termed as inner transition elements because their formation of transition series within the d-block elements (transition elements).

Complete step by step answer:
Let's understand the f-block elements in detail. In this block, the filling of the last electron takes place in the (n-2)f subshell (also called antepenultimate sub-shell). At the same time, (n-1) d sub-shell contains zero or one electron and ns subshell has two electrons. The general configuration of f-block elements is,
$\left( {n - 2} \right){f^{1 - 14}}\left( {n - 1} \right){d^{0 - 1}}n{s^2}$
So, in inner transition elements the differentiating electron enters the f orbital.

So, the correct answer is Option D.

Additional Information:
Let's discuss transition elements in detail. Transition elements are present in the mid section
(group 3 to 12)of the periodic table. They are termed as transition elements because they are present between p-block and s-block elements. The general electronic configuration of transition elements is $\left( {n - 1} \right){d^{1 - 10}}n{s^{1 - 2}}$. The transition elements and their compounds possess catalytic properties.
Some examples of transition elements are, iron, zinc etc. The transition elements possess variable valency because of the presence of valence electrons in two sets of orbital, that is, (n-1) d and ns. Because of incomplete d-orbital they are colorful in nature. Colour of titanium is purple.

Note: Some characteristics associated with f-block elements are, they are heavy metals, they possess high melting and boiling points, the compounds of these elements are generally colored, most of the elements of the actinide series are radioactive in nature. The f-block elements are placed at the bottom of the periodic table.