Very Short Questions on Aldehydes & Ketones
1. What functional group is present in a compound that gives a positive Tollens’ test? Also
write the reaction.
2. Give an example of an aliphatic aldehyde which gives aldol condensation reaction.
3. What is Cannizzaro’s reaction? Give one example.
4. Which has higher boiling points—aldehydes and ketones or their corresponding alkanes and
ethers? Why?
5. Convert ethanal to propanal.
6. Convert methanal to ethanal.
7. Explain the hybridisation present in the carbonyl carbon of aldehydes and ketones.
8. What is formalin?
9. What happens when acetylene gas is passed through HgSO₄ in presence of dil. H₂SO₄?
10. Why is acetone soluble in water but acetophenone is not?
11. Boiling points of aldehydes and ketones are lower than those of the corresponding alcohols.
Why?
12. How is Fehling’s test performed and for what purpose?
13. Using dialkyl cadmium, how do you prepare 2-butanone?
14. Aldehydes are more reactive than ketones towards nucleophilic addition reaction. Why?
15. Write the reaction of acetone with semicarbazide.
16. What happens when benzaldehyde is heated with aqueous NaOH solution?
17. What products are obtained when 3-methyl-1-butene is subjected to ozonolysis?
18. Explain why aldehydes are easily oxidised and act as good reducing agents, but ketones do
not.
19. Write a reaction where an aldehyde acts as a reducing agent.
20. Distinguish between formaldehyde and acetaldehyde.
21. Can formaldehyde give Cannizzaro’s reaction? Why or why not?
22. How are hydrazones of aldehydes and ketones prepared?
23. Write the reaction of acetone with H₂N–NH₂ in the presence of NaOH.
24. An alkene “A” on ozonolysis followed by hydrolysis produces acetone and ethanal. Identify
A.
25. Give possible isomeric structures of carbonyl compounds with the formula C₄H₈O.
26. What is Rosenmund reduction?
27. What is the preparative method of aldehydes and ketones by dehydrogenation of alcohols?
28. Prepare acetone from an alkyne.
29. “NaHSO₃ can be used to separate carbonyl compounds from others.” Justify.
30. Write the reaction of benzaldehyde with hydroxylamine (NH₂OH).
31. Why are aldehydes easily oxidised?
32. What is Wolff–Kishner reduction?
33. What happens when aldehydes and ketones are subjected to Clemmensen reduction?
34. Write a reaction of cross-aldol condensation.
35. Benzaldehyde does not give Fehling’s test. Why?
36. Convert propanal to ethanal.
37. What is iodoform test? What type of organic compounds give this test? Write the
importance of iodoform test.
38. Nucleophilic addition reaction is a common reaction of aldehydes and ketones. Explain with an
example.
1. What functional group is present in a compound that gives a positive Tollens’ test? Also
write the reaction.
2. Give an example of an aliphatic aldehyde which gives aldol condensation reaction.
3. What is Cannizzaro’s reaction? Give one example.
4. Which has higher boiling points—aldehydes and ketones or their corresponding alkanes and
ethers? Why?
5. Convert ethanal to propanal.
6. Convert methanal to ethanal.
7. Explain the hybridisation present in the carbonyl carbon of aldehydes and ketones.
8. What is formalin?
9. What happens when acetylene gas is passed through HgSO₄ in presence of dil. H₂SO₄?
10. Why is acetone soluble in water but acetophenone is not?
11. Boiling points of aldehydes and ketones are lower than those of the corresponding alcohols.
Why?
12. How is Fehling’s test performed and for what purpose?
13. Using dialkyl cadmium, how do you prepare 2-butanone?
14. Aldehydes are more reactive than ketones towards nucleophilic addition reaction. Why?
15. Write the reaction of acetone with semicarbazide.
16. What happens when benzaldehyde is heated with aqueous NaOH solution?
17. What products are obtained when 3-methyl-1-butene is subjected to ozonolysis?
18. Explain why aldehydes are easily oxidised and act as good reducing agents, but ketones do
not.
19. Write a reaction where an aldehyde acts as a reducing agent.
20. Distinguish between formaldehyde and acetaldehyde.
21. Can formaldehyde give Cannizzaro’s reaction? Why or why not?
22. How are hydrazones of aldehydes and ketones prepared?
23. Write the reaction of acetone with H₂N–NH₂ in the presence of NaOH.
24. An alkene “A” on ozonolysis followed by hydrolysis produces acetone and ethanal. Identify
A.
25. Give possible isomeric structures of carbonyl compounds with the formula C₄H₈O.
26. What is Rosenmund reduction?
27. What is the preparative method of aldehydes and ketones by dehydrogenation of alcohols?
28. Prepare acetone from an alkyne.
29. “NaHSO₃ can be used to separate carbonyl compounds from others.” Justify.
30. Write the reaction of benzaldehyde with hydroxylamine (NH₂OH).
31. Why are aldehydes easily oxidised?
32. What is Wolff–Kishner reduction?
33. What happens when aldehydes and ketones are subjected to Clemmensen reduction?
34. Write a reaction of cross-aldol condensation.
35. Benzaldehyde does not give Fehling’s test. Why?
36. Convert propanal to ethanal.
37. What is iodoform test? What type of organic compounds give this test? Write the
importance of iodoform test.
38. Nucleophilic addition reaction is a common reaction of aldehydes and ketones. Explain with an
example.
