Question

Match the LIST-I with LIST-II: 

 

Choose the correct answer from the options given below :

• A. A-IV, B-II, C-I, D-III
• B. A-III, B-II, C-I, D-IV
• C. A-IV, B-I, C-III, D-II
• D. A-II, B-IV, C-III, D-I

Hint:

Remember that the octet rule applies to molecules where atoms aim to achieve 8 electrons in their outer shell. However, molecules with an odd number of electrons or those with more than 8 electrons on the central atom do not strictly follow this rule.

Answer 1

The Correct Option is A

To solve this matching problem, we need to correctly associate each category of molecules (LIST-I) with the appropriate example (LIST-II) based on the octet rule. Let's break down each pair: 

1. Molecules obeying octet rule (A): These are molecules in which all atoms achieve a stable configuration of 8 electrons in their valence shells. Common examples include simple molecules like CO₂ and CCl₄. Therefore, the match is A-IV (CCl₄, CO₂).
2. Molecules with incomplete octet (B): These molecules do not have a complete octet around one or more of their atoms. Boron compounds like BCl₃ and AlCl₃ often exhibit incomplete octets. Therefore, the match is B-II (BCl₃, AlCl₃).
3. Molecules with incomplete octet with odd electron (C): Certain molecules like NO and NO₂ possess an odd number of electrons, and thus, not all atoms can achieve an octet. Therefore, the match is C-I (NO, NO₂).
4. Molecules with expanded octet (D): Some elements in the third period or below can expand their valence shell beyond 8 electrons. Examples include PCl₅ and H₂SO₄, where elements like phosphorus or sulfur have expanded octets. Therefore, the match is D-III (H₂SO₄, PCl₅).

Based on the reasoning above, the correct matching is:

A-IV, B-II, C-I, D-III

Answer 2

(A) Molecules obeying octet rule: Molecules like CO2 and CCl4 obey the octet rule, where each atom completes its octet. Hence, A corresponds to IV. 

(B) Molecules with incomplete octet: Molecules such as BCl3 and AlCl3 have an incomplete octet on the central atom. Hence, B corresponds to II.

(C) Molecules with incomplete octet with odd electron: NO and NO2 have an odd number of electrons and an incomplete octet. Hence, C corresponds to I. 

(D) Molecules with expanded octet: Molecules like H2SO4 and PCl5 have an expanded octet, which means the central atoms have more than eight electrons. Hence, D corresponds to III. 

Thus, the correct matching is A-IV, B-II, C-I, D-III.