Which of the following sets of elements has the most similar physical and chemical properties?

• A. He, Ne, Ar
• B. Na, K, Rb
• C. Fe, Cu, Zn
• D. C, N, O

Answer: (B)

Verified step by step guidance

1. Step 1: Understand that elements with the most similar physical and chemical properties are typically found in the same group (vertical column) of the periodic table because they have the same number of valence electrons.
2. Step 2: Identify the groups of each set of elements: He, Ne, Ar are all noble gases in Group 18; Na, K, Rb are alkali metals in Group 1; Fe, Cu, Zn are transition metals but belong to different groups (Fe in Group 8, Cu in Group 11, Zn in Group 12); C, N, O are nonmetals but belong to different groups (Group 14, 15, and 16 respectively).
3. Step 3: Recognize that elements in the same group (like Na, K, Rb) have very similar chemical properties because they have the same number of valence electrons, which governs their reactivity and bonding behavior.
4. Step 4: Compare the physical and chemical properties of the sets: noble gases (He, Ne, Ar) are similar but differ significantly in atomic size and boiling points; transition metals (Fe, Cu, Zn) have different properties due to their different electron configurations; nonmetals (C, N, O) differ widely in properties due to their different groups.
5. Step 5: Conclude that the set Na, K, Rb has the most similar physical and chemical properties because they are all alkali metals in the same group, sharing similar valence electron configurations and thus similar reactivity and physical characteristics.