During the reduction of sugar through Fehling's solution, the ionic state of metal changes from:
Correct answer: D. Cu+2 to Cu+1
- A. Fe+2 to Fe+3
- B. Fe+3 to Fe+5
- C. Cu+1 to Cu+2
- D. Cu+2 to Cu+1
Explanation
During the reduction of sugar through Fehling's solution, the ionic state of metal changes from Cu²⁺ to Cu₂O. Fehling's solution is a deep blue alkaline solution that contains copper ions in the Cu²⁺ state. When a reducing sugar such as glucose is added to Fehling's solution and heated, it reduces the Cu²⁺ ions to Cu⁺ ions, which then react with hydroxide ions in the solution to form a reddish-brown precipitate of Cu₂O. This reaction is used to detect the presence of reducing sugars in a sample.
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