Question

On descending the group from Li to Na to K to Rb to Cs

(A) Metallic radius increases
(B) Melting point and boiling point decrease
(C) Density decreases
(D) Ionization energy decreases
Choose the correct answer from the options given below:

• A. (A) and (B) only.
• B. (B) and (C) only.
• C. (A), (B) and (D) only.
• D. (A), (C) and (D) only.

Hint:

As you go down Group 1 (alkali metals): metallic radius increases, ionization energy decreases, and melting/boiling points generally decrease.

Answer 1

The Correct Option is C

Step 1: Analyze periodic trends.
- Metallic radius increases as we go down the group because the atoms get larger due to the addition of electron shells.
- Melting point and boiling point decrease as we move down the group because the metallic bonds weaken due to increased atomic size.
- Density increases, not decreases, as you go down the group because the atoms get larger and more massive.
- Ionization energy decreases as we move down the group because the outermost electron is farther from the nucleus and more shielded by inner electrons.
Step 2: Conclusion. Thus, the correct options are (A), (B), and (D).
Final Answer: \[ \boxed{\text{(A), (B) and (D) only}} \]