Which of the following statements correctly describes the first 30 elements of the periodic table?

• A. All of them are classified as transition metals.
• B. They are all nonmetals.
• C. None of them are representative elements.
• D. They include both representative elements and transition metals.

Answer: (D)

Verified step by step guidance

1. Understand the classification of elements in the periodic table: elements are grouped into representative elements (also called main-group elements), transition metals, and inner transition metals based on their electron configurations and properties.
2. Recall that the first 30 elements include elements from hydrogen (1) to zinc (30), covering periods 1 to 4 of the periodic table.
3. Identify that representative elements are found in groups 1, 2, and 13 to 18, which include metals, metalloids, and nonmetals, while transition metals are found in groups 3 to 12.
4. Recognize that among the first 30 elements, some belong to the representative groups (such as sodium, magnesium, and aluminum) and some belong to the transition metals (such as scandium, titanium, and zinc).
5. Conclude that the first 30 elements include both representative elements and transition metals, so the correct description is that they include both types.