Which of the following chemical elements is a metal: selenium (Se), iodine (I), zinc (Zn), or sulfur (S)?

Introduction / Context:
The periodic table distinguishes metals, nonmetals, and metalloids, each group having characteristic physical and chemical properties. Metals are typically lustrous, malleable, ductile, and good conductors of heat and electricity, while nonmetals tend to be dull, brittle when solid, and poor conductors. This question asks you to identify which element among selenium, iodine, zinc, and sulfur is a metal, drawing on basic knowledge of periodic trends and elemental classification.

Given Data / Assumptions:

• Selenium (Se) lies in group 16 of the periodic table.
• Iodine (I) is a halogen in group 17.
• Zinc (Zn) is a transition element in group 12.
• Sulfur (S) is a chalcogen in group 16.
• Metals are usually found on the left and in the central block of the periodic table, while nonmetals are on the right.

Concept / Approach:
Most elements in the p-block on the right side of the periodic table are nonmetals or metalloids, especially in the upper part of the table. Selenium and sulfur are chalcogens that behave as nonmetals under normal conditions. Iodine is a halogen and is also classified as a nonmetal, although it has some metallic sheen in solid form. Zinc, on the other hand, is a d-block element and is clearly classified as a metal. It is commonly used in galvanisation and alloys and exhibits typical metallic properties. Therefore, among the listed elements, zinc is the metal.

Step-by-Step Solution:
Step 1: Identify the positions of the elements in the periodic table. Selenium and sulfur are in group 16, iodine is in group 17, and zinc is in group 12. Step 2: Recall that group 16 elements such as oxygen, sulfur, and selenium are generally treated as nonmetals or metalloids, with sulfur and selenium behaving as nonmetals in standard conditions. Step 3: Note that iodine belongs to the halogen group, which consists of nonmetals like fluorine, chlorine, bromine, and iodine. Step 4: Recognise that zinc is located among the transition metals and has metallic properties such as conductivity and malleability. Step 5: Conclude that zinc (Zn) is the only metal among the options.

Verification / Alternative check:
Look at how these elements are used in practice. Sulfur is used in vulcanisation of rubber and production of sulphuric acid but is a brittle, yellow solid, typical of a nonmetal. Selenium is used in electronics and glass colouring but is considered a nonmetal or metalloid. Iodine is used in antiseptics and as a nutrient and appears as a dark crystalline solid that sublimes easily, another sign of nonmetal behaviour. Zinc, by contrast, is used as a metal coating for galvanised iron, in batteries, and in alloys like brass, demonstrating metallic conduction and malleability. These real world applications reflect its classification as a metal.

Why Other Options Are Wrong:
Selenium is not classified as a metal; it is closer to nonmetals and metalloids, and it does not exhibit classic metallic behaviour. Iodine is a nonmetal halogen, even though its crystals shine; its chemical behaviour is nonmetallic. Sulfur is a well known nonmetal with low electrical conductivity and brittle nature. The option that none of the elements is metallic is incorrect because zinc is clearly a metal both in theory and in everyday use.

Common Pitfalls:
Students may be tempted by iodine because solid iodine crystals look shiny and metallic. However, appearance alone does not define metals; chemical behaviour and position in the periodic table also matter. Another pitfall is to misplace zinc mentally into the p-block and treat it as a nonmetal. To avoid such errors, remember that zinc is a familiar metal used on roofs and in batteries and that the d-block region is dominated by metals.

Final Answer:
Among the given elements, the metal is Zn (zinc).