an example of a transition element having completely filled d-orbital is

zn
Ti
v
Cr

You are therefore looking for elements in Group 12 (s2 + d10)

which are Zn, Cd and Hg

An example of a transition element having a completely filled d-orbital is zinc (Zn).

An example of a transition element that has a completely filled d-orbital is Zinc (Zn).

Here's how you can determine this:

1. Identify the electron configuration of the element:
The electron configuration of zinc can be determined by referring to the periodic table. Zinc is located in the 4th period, column 12, of the periodic table, so its atomic number is 30. The electron configuration of zinc is [Ar] 3d10 4s2.

2. Examine the d-orbital:
In the electron configuration, the number before the "d" represents the number of electrons in the d-orbital. In the case of zinc, there are 10 electrons in the 3d-orbital.

3. Determine if the d-orbital is completely filled:
Since the maximum number of electrons that can occupy the 3d-orbital is 10, and zinc has exactly 10 electrons in the 3d-orbital, we can conclude that the d-orbital is completely filled in zinc.

In contrast, elements like Titanium (Ti), Vanadium (V), and Chromium (Cr) have incomplete d-orbitals. Titanium has an electron configuration of [Ar] 3d2 4s2, Vanadium has an electron configuration of [Ar] 3d3 4s2, and Chromium has an electron configuration of [Ar] 3d5 4s1. Therefore, none of these elements have completely filled d-orbitals.