1. Identify each class in List I

• (A) Molecules obeying octet rule: central atom completes 8 electrons.
• (B) Molecules with incomplete octet: central atom has fewer than 8 electrons.
• (C) Molecules with incomplete octet with odd electron: odd-electron molecules, so octet cannot be completed.
• (D) Molecules with expanded octet: central atom has more than 8 electrons.

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2. Match with examples in List II

(A) Molecules obeying octet rule

Examples: $\mathrm{CCl}_4, \mathrm{CO}_2$

• In $\mathrm{CCl}_4$, carbon has 4 bonds $\Rightarrow 8$ electrons around C.
• In $\mathrm{CO}_2$, carbon forms two double bonds $\Rightarrow 8$ electrons around C.

So, $A \to IV$

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(B) Molecules with incomplete octet

Examples: $\mathrm{BCl}_3, \mathrm{AlCl}_3$

• In $\mathrm{BCl}_3$, boron has only 6 electrons around it.
• In $\mathrm{AlCl}_3$, aluminium also has incomplete octet.

So, $B \to II$

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(C) Molecules with incomplete octet with odd electron

Examples: $\mathrm{NO}, \mathrm{NO}_2$

• Both have odd total number of valence electrons.
• Hence they are odd-electron molecules and cannot satisfy complete octet for all atoms.

So, $C \to I$

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(D) Molecules with expanded octet

Examples: $\mathrm{H}_2\mathrm{SO}_4, \mathrm{PCl}_5$

• In $\mathrm{PCl}_5$, phosphorus has 10 electrons around it.
• In $\mathrm{H}_2\mathrm{SO}_4$, sulfur can have expanded valence shell.

So, $D \to III$

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3. Final matching

$A-IV,\; B-II,\; C-I,\; D-III$

This corresponds to Option C.

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4. Comparison with stored answer

Stored correct answer: C

Derived answer: C

Hence, the derived answer agrees with the stored answer.