The composition of Fehling solution A and Fehling solution B respectively are

The aqueous solution of copper sulphate and alkaline sodium potassium tartarate respectively

The correct answer is Option (4) → The aqueous solution of copper sulphate and alkaline sodium potassium tartarate respectively

• Fehling’s solution is prepared in two separate solutions:

1. Fehling A: Copper(II) sulfate solution (CuSO₄·5H₂O)
2. Fehling B: Alkaline solution of sodium potassium tartrate (Rochelle salt) in NaOH)

• When mixed in equal volumes before use, it is used to test reducing sugars.
• The tartrate complex prevents the precipitation of Cu(OH)₂ in alkaline medium, allowing the reaction to occur smoothly.

Hence, Fehling A = CuSO₄, Fehling B = sodium potassium tartrate solution.

Correct answer: The aqueous solution of sodium potassium tartarate and copper sulphate respectively