Question

Given below are two statements:
Statement I: The metallic radius of Na is 1.86 Å and the ionic radius of Na$^+$ is lesser than 1.86 Å.
Statement II: Ions are always smaller in size than the corresponding elements.
In the light of the above statements, choose the correct answer from the options given below:

• A. Statement I is correct but Statement II is false
• B. Both Statement I and Statement II are true
• C. Both Statement I and Statement II are false
• D. Statement I is incorrect but Statement II is true

Answer 1

The Correct Option is A

Step 1: Analysis of Statement I
- The metallic radius of N a (neutral sodium atom) is 1.86 ̊A.
- The ionic radius of Na⁺ is smaller than the neutral atom because Na⁺ has one less electron, resulting in reduced electron-electron repulsion and greater effective nuclear charge on the remaining electrons. - Thus, Statement I is correct.
Step 2: Analysis of Statement II - While cations (Na⁺) are always smaller than their corresponding neutral atoms, anions (e.g., Cl^-) are larger than their corresponding neutral atoms due to increased electron-electron repulsion in the outer shell.
- Hence, ions are not always smaller than the corresponding elements.
- Thus, Statement II is false.
Step 3: Conclusion - Statement I is correct, but Statement II is false.
Final Answer: (1)

Answer 2

Step 1: Analyze Statement I.
Statement I: The metallic radius of Na is 1.86 Å and the ionic radius of Na⁺ is lesser than 1.86 Å.
Explanation: When sodium loses one electron to form Na⁺, the outermost shell (3s¹) is removed completely, resulting in a smaller electron cloud. The number of protons remains the same, but the number of electrons decreases, increasing the effective nuclear charge. Hence, Na⁺ is much smaller than Na.
Therefore, Statement I is correct.

Step 2: Analyze Statement II.
Statement II: Ions are always smaller in size than the corresponding elements.
Explanation: This is not always true. While cations (like Na⁺) are smaller than their parent atoms, anions (like Cl⁻) are larger than their parent atoms due to increased electron-electron repulsion and decreased effective nuclear charge per electron.
Therefore, Statement II is false.

Step 3: Conclusion.
Statement I is correct but Statement II is false.

Final Answer: Statement I is correct but Statement II is false.