Question detail
What is the main observation when Fehling's reagent is added to an aldehyde?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Aldehydes and ketones (A-level only)
Question
- A. Formation of a red precipitate
- B. No change in color
- C. Formation of a blue solution
- D. Production of a gas
Answer
Formation of a red precipitate
Explanation
The correct option is Formation of a red precipitate. Formation of a red precipitate is the best answer because it directly supports the AQA A-Level Chemistry objective to use Tollens' and Fehling's reagents to distinguish aldehydes from ketones. This reasoning is anchored to Aldehydes and ketones (A-level only) in Aldehydes and ketones (A-level only), and it separates Fehling from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.
Common mistake
Confusing Aldehydes and Ketones
Students often confuse aldehydes and ketones, thinking they are the same due to both containing a carbonyl group.
Remember that aldehydes have the carbonyl group at the end of the carbon chain, while ketones have it within the chain.
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