Which of the following best describes the elements in the first group of the periodic table?

• A. They are noble gases and are chemically inert.
• B. They are transition metals and have variable oxidation states.
• C. They are halogens and form salts with metals.
• D. They are known as alkali metals and are highly reactive.

Answer: (D)

Verified step by step guidance

1. Identify the first group of the periodic table, which is Group 1 (also called Group IA).
2. Recall the characteristics of Group 1 elements: they are known as alkali metals.
3. Understand that alkali metals are highly reactive, especially with water, and have a single electron in their outermost shell.
4. Compare the given options with the known properties of Group 1 elements: they are not noble gases, transition metals, or halogens.
5. Conclude that the best description is that they are alkali metals and are highly reactive.