### Correct Option: A. Acetic acid + ethanol → ethyl acetate + water #### Explanation of Why Option A is Correct: A condensation reaction is a type of chemical reaction where two molecules combine to form a larger molecule, with the simultaneous loss of a small molecule, often water. In the case of option A, acetic acid (CH₃COOH) reacts with ethanol (C₂H₅OH) to form ethyl acetate (CH₃COOC₂H₅) and water (H₂O). **Step-by-Step Breakdown:** 1. **Reactants**: The reactants are acetic acid and ethanol. - Acetic acid has a carboxylic acid functional group (-COOH). - Ethanol has a hydroxyl group (-OH). 2. **Reaction Mechanism**: - The hydroxyl group (-OH) from acetic acid and a hydrogen atom (H) from the hydroxyl group of ethanol combine to form water (H₂O). - The remaining parts of the molecules (the acyl group from acetic acid and the ethyl group from ethanol) bond together to form ethyl acetate. 3. **Products**: The products of this reaction are ethyl acetate and water. - Ethyl acetate is an ester, which is formed through the condensation of an alcohol and a carboxylic acid. 4. **Overall Reaction**: \[ \text{CH}_3\text{COOH} + \text{C}_2\text{H}_5\text{OH} \rightarrow \text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O} \] This reaction exemplifies a condensation reaction because it involves the formation of a new bond (the ester bond) and the release of water. #### Why the Other Options are Incorrect: - **Option B: Ethylene + chlorine → dichloroethane** - This reaction is an example of an addition reaction, not a condensation reaction. In this case, ethylene (C₂H₄) reacts with chlorine (Cl₂) to form dichloroethane (C₂H₄Cl₂) without the loss of any small molecule. The double bond in ethylene is broken, and chlorine atoms are added across the double bond. - **Option C: Chlorine + water → hydrochloric acid + oxygen** - This reaction is a redox reaction and not a condensation reaction. Chlorine reacts with water to produce hydrochloric acid (HCl) and oxygen (O₂). There is no formation of a larger molecule from smaller ones with the loss of a small molecule. - **Option D: Nitrogen + oxygen → nitrogen oxide** - This reaction is a combination reaction, where nitrogen (N₂) and oxygen (O₂) combine to form nitrogen oxides (NO or NO₂). Similar to option C, this does not involve the loss of a small molecule and does not fit the definition of a condensation reaction. ### Summary: - **Condensation Reaction**: Involves the combination of two molecules with the loss of a small molecule (often water). - **Correct Example**: Acetic acid and ethanol form ethyl acetate and water, demonstrating a condensation reaction. - **Other Options**: - Option B is an addition reaction. - Option C is a redox reaction. - Option D is a combination reaction. ### Revision Summary: - A condensation reaction produces a larger molecule and releases a small molecule (like water). - Acetic acid + ethanol → ethyl acetate + water is a classic example of a condensation reaction. - Addition, redox, and combination reactions do not fit the criteria for condensation reactions.