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: Periodic Trend Analysis.
- Metallic radius increases down a group as atoms grow larger due to added electron shells.
- Melting and boiling points decrease down a group because metallic bonds weaken with increasing atomic size.
- Density increases down a group due to larger and more massive atoms.
- Ionization energy decreases down a group because the outermost electron is further from the nucleus and more shielded.
Step 2: Conclusion. Therefore, options (A), (B), and (D) are correct.
Final Answer: \[ \boxed{\text{(A), (B) and (D) only}} \]