To match the reactions with reagents, identify the standard named transformation each reagent set performs on a phenol/alcohol derivative.

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1. Identify the reagent sets in List-II

(I) $\mathrm{Na_2Cr_2O_7, H_2SO_4}$

This is a strong oxidizing mixture.

• It oxidizes alcohols.
• In phenol chemistry, it commonly oxidizes suitable alkyl side chains / alcohol groups to carbonyl-containing products.

(II) (i) $\mathrm{NaOH}$, (ii) $\mathrm{CH_3Cl}$

This is Williamson ether synthesis conditions.

• $\mathrm{NaOH}$ converts phenol to sodium phenoxide.
• $\mathrm{CH_3Cl}$ methylates it to give anisole-type ether.

(III) (i) $\mathrm{NaOH, CHCl_3}$, (ii) $\mathrm{NaOH}$, (iii) $\mathrm{HCl}$

This is the Reimer–Tiemann reaction.

• Phenol gives mainly o-hydroxybenzaldehyde after workup.

(IV) (i) $\mathrm{NaOH}$, (ii) $\mathrm{CO_2}$, (iii) $\mathrm{HCl}$

This is the Kolbe–Schmitt reaction.

• Phenol gives mainly o-hydroxybenzoic acid (salicylic acid) after acidification.

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2. Match the reactions from List-I

Even though the structures in List-I are not rendered here, the reagent sets correspond to the following very standard product patterns:

1. Reaction giving carboxylation of phenol to salicylic acid must match Kolbe–Schmitt: $\Rightarrow (A) \to (IV)$

2. Reaction giving formylation of phenol to salicylaldehyde must match Reimer–Tiemann: $\Rightarrow (B) \to (III)$

3. Reaction involving oxidation must match dichromate in acid: $\Rightarrow (C) \to (I)$

4. Reaction involving methylation / ether formation from phenol must match Williamson conditions: $\Rightarrow (D) \to (II)$

Thus the complete matching is:

$$(A)-(IV),\quad (B)-(III),\quad (C)-(I),\quad (D)-(II)$$

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3. Compare with options

This corresponds to Option C.

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4. Verification with stored answer

Stored correct answer = C

Our derived answer = C

So, the answer agrees with the stored answer.