Identify A and B in the following reaction
`C_(2)H_(5) - Cl overset(A)rarr C_(2)H_(5) OH overset(B)leftarrow C_(2)H_(5)Cl`

Options

A. A = aqueous KOH, B = moist `Ag_(2)O`
B. A = alcoholic KOH, B = aqueous NaOH
C. A = aqueous NaOH, B `= AgNO_(2)`
D. `A = AgNO_(2), B = KNO_(2)`

Answer

To identify A and B in the given reaction, we need to analyze the transformations occurring in the reaction sequence involving ethyl chloride (C₂H₅Cl) and ethyl alcohol (C₂H₅OH).

### Step 1: Identify the first transformation (A)
The first part of the reaction shows the conversion of ethyl chloride (C₂H₅Cl) to ethyl alcohol (C₂H₅OH). This transformation involves the substitution of the chlorine atom (Cl) with a hydroxyl group (OH).

To achieve this, we can use a nucleophilic substitution reaction. The most common reagents for this transformation are:
- Aqueous sodium hydroxide (NaOH)
- Aqueous potassium hydroxide (KOH)

In this case, we can choose **A = NaOH (aqueous)** as the reagent that facilitates this transformation. The hydroxide ion (OH⁻) from NaOH acts as a nucleophile, attacking the carbon atom bonded to the chlorine, leading to the formation of C₂H₅OH.

### Step 2: Identify the second transformation (B)
The second part of the reaction shows the reverse transformation, where ethyl alcohol (C₂H₅OH) is converted back to ethyl chloride (C₂H₅Cl). This transformation typically involves the conversion of an alcohol to an alkyl halide, which can be accomplished through a reaction with a reagent that introduces the chlorine atom.

One common method to convert alcohols to alkyl halides is to use thionyl chloride (SOCl₂) or phosphorus trichloride (PCl₃). However, in this context, we can also consider the reaction of the alcohol with hydrochloric acid (HCl) in the presence of a dehydrating agent.

Thus, we can choose **B = HCl** as the reagent that facilitates this transformation.

### Final Answer
- A = NaOH (aqueous)
- B = HCl