Which one of the following is a transition metal?

Manganese (Mn) is a transition metal located in the first transition series of the d-block in the periodic table [t1][t2]. Transition metals are defined as elements that have an incomplete d-subshell in their neutral atom or ionic state [t2][t5]. Manganese, with atomic number 25, fits this definition as it fills the 3d orbitals [t1][t2]. In contrast, Magnesium (Mg) and Calcium (Ca) are classified as alkaline earth metals belonging to Group 2 of the s-block [t1][t3]. Aluminium (Al) is a post-transition metal (or poor metal) located in Group 13 of the p-block [t1][t3]. While elements like Scandium to Zinc are often discussed within the first transition series, Manganese is a classic example of a transition element due to its variable oxidation states and electronic configuration [t2][t8].

Sources

1. [1] https://www.energy.gov/sites/prod/files/2020/07/f76/The%20Periodic%20Table%20of%20Elements.pdf