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Class 12 Chemistry (Part Ii) Chapter 12 Aldehydes Quiz 1 (25 MCQs)

Quiz Instructions

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1. What observation indicates a positive Fehling's test?

Correct Answer: C) A red precipitate forms.

2. Reaction of aldehydes with primary amine will results in the formation of

Correct Answer: C) An imine.

3. Which of the following will not give the iodoform test

Correct Answer: C) Benzophenone.

4. Acetophenone is prepared by

Correct Answer: A) Friedel craft reaction.

5. What is the name of the mechanism when KCN (in acidic conditions) reacts with propanal?

Correct Answer: C) Nucleophilic addition.

6. What is the product of the reaction between a carboxylic acid and an alcohol?

Correct Answer: C) Ester.

7. What type of reaction is involved in the dehydration of alcohols to form aldehydes or ketones?

Correct Answer: A) Elimination reaction.

8. What is the role of a catalyst in the oxidation of aldehydes?

Correct Answer: D) Speeds up the oxidation reaction by providing an alternative pathway with lower activation energy.

9. The oxidising agent in the Tollens' test for the presence of an aldehyde is .....

Correct Answer: A) Ag$^{+}$.

10. When a tertiary alcohol reacts with acidified dichromate:

Correct Answer: C) The alcohol is not oxidised.

11. The simplest aliphatic ketone

Correct Answer: B) Acetone.

12. When ethanoic acid reacts with magnesium, which gas is released?

Correct Answer: C) Hydrogen.

13. Reaction of a carboxylic acid and a primary amine will produce:

Correct Answer: D) An amide if heat is added.

14. The correct order of acidic strength of carboxylic acids is

Correct Answer: D) Acetic acid < benzoic acid < Formic acid.

15. Which alcohol must be oxidized to obtain propanone (acetone)?

Correct Answer: D) 2-propanol.

16. The Clemmenson reduction of acetone yields

Correct Answer: C) Propane.

17. What happens when carbon dioxide is tested with a lighted taper?

Correct Answer: C) The flame goes out.

18. The product formed in Aldol condensation is

Correct Answer: C) A beta hydroxy aldehyde or ketone.

19. On oxidizing compound X with CrO$_{3 }$, compound Y is obtained. Compound Y does not react with Tollens reagent. X and Y are most likely to be,

Correct Answer: C) X:CH$_{3}$CH(OH)CH$_{3}$ Y:CH$_{3}$COCH$_{3}$.

20. The only aldehyde that gives positive result with I$_{2}$/NaOH is

Correct Answer: C) Ethanal.

21. What is R?CH$_{3}$CH$_{2}$COH + R $\rightarrow$ CH$_{3}$CH$_{2}$COOH

Correct Answer: C) Na$_{2}$Cr$_{2}$O$_{7}$ / H$^{+}$.

22. What is the key reagent used in the Stephen reaction for aldehyde synthesis?

Correct Answer: D) Bromine (Br2).

23. Which reagent is NOT commonly used for the oxidation of primary alcohols to aldehydes?

Correct Answer: C) Sodium ethanoate (CH3COONa).

24. Alcohol forms over time through the process of fermentation, when ..... sugars breakdown.

Correct Answer: C) Carbohydrate.

25. Which of the following tests would give a positive result for propan-1-ol?

Correct Answer: C) PCl$_{5}$ (phosphorus pentachloride).

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