Answer :
Final answer:
Selenium is a nonmetal, strontium is a metal, and antimony is incorrectly classified as a metalloid instead of a metal.
Explanation:
Based on its position in the periodic table, selenium (Se) is classified as a nonmetal. Selenium lies above and to the right of the diagonal line marking the boundary between metals and nonmetals in the periodic table. Therefore, it falls into the nonmetal category.
On the other hand, strontium (Sr) is correctly classified as a metal. It lies well to the left of the diagonal belt of metalloids and is found in the metal region of the periodic table.
Therefore, the element that is incorrectly classified in terms of its classification as a metal, nonmetal, or metalloid is antimony (Sb). Antimony is classified as a metalloid, when in fact it should be classified as a metal. It is located to the left of the diagonal belt of metalloids, similar to strontium (Sr).
