NEET-UG and JEE Main Chemistry · Class 12
Detection of functional groups — NEET & JEE Questions
Detection of functional groups is a topic in Principles Related to Practical Chemistry, a Class 12 Chemistry chapter of the NEET-UG and JEE Main syllabus. TestBudy holds 12 published NEET-UG and JEE Main questions on Detection of functional groups, each with the marking scheme of the real paper.
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Detection of functional groups MCQs with solutions
10 of the 12 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
Which observation is expected when a carboxylic acid is treated with aqueous sodium hydrogen carbonate?
- A. Effervescence due to carbon dioxide
- B. A silver mirror on the test tube
- C. A violet colour with neutral ferric chloride
- D. A brick-red precipitate without heating
Neutral ferric chloride is commonly used to detect which functional class by a characteristic coloured complex?
- A. Alkanes
- B. Phenols
- C. Ethers
- D. Haloalkanes
Two colourless liquids both react with 2,4-DNP. Only liquid X gives a silver mirror with Tollens' reagent. What distinguishes X from the other liquid?
- A. X is a carboxylic acid whereas the other liquid is an ester
- B. X is a ketone whereas the other liquid is an aldehyde
- C. X is an alcohol whereas the other liquid is an ether
- D. X is an aldehyde whereas the other liquid is a ketone
Which observation is a characteristic positive test for a carboxylic acid when sodium bicarbonate is added?
- A. A silver mirror forms
- B. Brisk effervescence of carbon dioxide occurs
- C. A violet colour appears with neutral ferric chloride
- D. A yellow precipitate forms with iodine immediately
A compound gives an orange precipitate with 2,4-dinitrophenylhydrazine but does not give Tollens' test. Which class best fits the observations?
- A. Carboxylic acid
- B. Primary alcohol
- C. Ketone
- D. Alkane
An organic liquid gives an orange-yellow precipitate with 2,4-DNP reagent. Which functional group class is indicated?
- A. Ether only
- B. Alkene only
- C. Aldehyde or ketone
- D. Carboxylate salt only
A compound gives a silver mirror with Tollens' reagent. Which functional group is most strongly indicated in the usual qualitative test?
- A. Aldehyde
- B. Ketone
- C. Ether
- D. Alkane
A phenolic compound is treated with neutral ferric chloride solution. Which observation commonly supports the presence of phenolic -OH?
- A. Evolution of carbon dioxide
- B. Formation of a coloured complex, often violet
- C. Silver mirror formation
- D. Immediate decolourisation of every reagent
An unknown compound gives a positive 2,4-DNP test but a negative Tollens' test. Which functional group is most consistent?
- A. A ketone
- B. An aldehyde
- C. A carboxylic acid
- D. A phenol
An unknown compound produces carbon dioxide with sodium bicarbonate but does not give a 2,4-DNP precipitate. Which class is most likely?
- A. Ketone
- B. Aldehyde
- C. Carboxylic acid
- D. Ether
Common mistakes in Detection of functional groups
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Applies the carbylamine test to all amines regardless of class.
- Treats one general carbonyl test as sufficient to assign aldehyde versus ketone.
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