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Class 12 Chemistry (Part Ii) Chapter 12 Aldehydes Quiz 5 (25 MCQs)

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1. In Fehling's test, which ion is reduced by an aldehyde?

Correct Answer: B) Cu2+.

2. Iodoform test:Pale yellow ppt2. Fehling's test:No observable change3. 2, 4-DNPH:yellow pptWhich compound will have the above observations?

Correct Answer: C) CH$_{3}$CH$_{2}$COCH$_{3}$.

3. Acetone reacts with HCN to form a cyanohydrin. It is an example of

Correct Answer: C) Nucleophilic addition.

4. What is the purpose of adding ammonia in Tollen's test?

Correct Answer: C) To dissolve the brown precipitate.

5. The functional group for aldehydes is:

Correct Answer: C) -CHO.

6. Carboxylic acids can be prepared by the oxidation of:

Correct Answer: D) All of the above.

7. Why does propanone not react in Fehling's test?

Correct Answer: C) It is a ketone and does not oxidise easily.

8. Benzaldehyde on nitration gives

Correct Answer: C) M-nitrobenzaldehyde.

9. Which is a test for a C=O?

Correct Answer: D) 2, 4-DNPH (Brady's reagent).

10. The boiling point for ethanoic acid is higher than propanol even when both these molecules have the same molecular mass. This is because

Correct Answer: A) Ethanoic acids can form dimmers through hydrogen bonding.

11. Which statement correctly compares Fehling's and Tollen's tests?

Correct Answer: C) Both tests distinguish aldehydes from ketones.

12. Which of the following is mandatory for aldol condensation reaction

Correct Answer: A) Presence of alpha hydrogen.

13. Which substance gives a positive result with Fehling's solution?

Correct Answer: C) Ethanal.

14. The reagent that does NOT oxidize aldehyde is

Correct Answer: C) Ag2O.

15. The functional group of aldehydes and ketones is

Correct Answer: B) Carbonyl.

16. On heating compound X with acidified KMnO$_{4}$, compound Y is obtained. Compound Y does not react with Fehling's solution. X and Y are most likely to be, Compound X Compound Y

Correct Answer: B) CH$_{3}$CH(OH)CH$_{3}$ CH$_{3}$COCH$_{3}$.

17. Which reaction involves the synthesis of aldehydes or ketones using carbon monoxide and hydrogen chloride?

Correct Answer: A) Rosenmund reduction.

18. Following reaction between an ylide and an alkyl halide, what other compund would be appropriate to produce a Wittig reagent?

Correct Answer: B) NaH.

19. Which pairing of test and gas is correct?

Correct Answer: C) Carbonate $\rightarrow$ CO2.

20. Which of the following compounds does not contain an-OH group

Correct Answer: C) Aldehydes.

21. When reacted with a strong oxidising agent, aldehydes turn into

Correct Answer: A) Carboxylic acids.

22. What is the product of the oxidation of propanal?

Correct Answer: A) Propanoic acid.

23. Tollens reagent will:

Correct Answer: C) Form a silver mirror.

24. What happens when an aldehyde is oxidized?

Correct Answer: D) Forms a carboxylic acid.

25. The number carboxylic acid group present in the product formed, when cyclohexene is oxidised with KMnO4 and dil.H2SO4

Correct Answer: B) 2.

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