one of the following is not a d-block element?

a.
Titanium

b.
Vanadium

c.
Aluminium

d.
Zinc

c. Aluminium

The correct answer is c. Aluminium. Aluminium is not a d-block element. It is a p-block element located in Group 13 of the periodic table. The d-block elements are transition metals, which include titanium (a), vanadium (b), and zinc (d).

To determine which of the given elements is not a d-block element, let's first understand what the d-block elements are.

The d-block elements are a group of elements found in the middle of the periodic table. They are characterized by having their outermost electron(s) in the d orbital of their electron configuration. The d orbitals can hold a maximum of 10 electrons.

Now, let's analyze each of the given elements:

a. Titanium (Ti) - Titanium is a transition metal, which is located in the d-block of the periodic table. It has an electron configuration of [Ar] 3d2 4s2, thus fulfilling the criteria of being a d-block element.

b. Vanadium (V) - Vanadium is also a transition metal and is part of the d-block. Its electron configuration is [Ar] 3d3 4s2, satisfying the requirement to be a d-block element.

c. Aluminium (Al) - Aluminium, on the other hand, is not a d-block element. It is classified as a p-block element. Aluminium is located in Group 13 of the periodic table and has the electron configuration [Ne] 3s2 3p1. It does not have any electrons in the d orbital, making it distinct from the d-block elements.

d. Zinc (Zn) - Zinc is another transition metal and is considered a d-block element. Its electron configuration is [Ar] 3d10 4s2, meeting the criteria for a d-block element.

Therefore, the correct answer is c. Aluminium, which is not a d-block element.