Question

Reducing sugars like glucose in Fehling solution reduce

• A. $C{u}^{+}$ to $C{u}^{++}$
  
• B. $F{e}^{++}$ to $F{e}^{+++}$
  
• C. $H{g}^{++}$ to $H{g}^{+}$
  
• D. $C{u}^{++}$ to $C{u}^{+}$
  

Answer 1

The correct option is D

$C{u}^{++}$ to $C{u}^{+}$

Reducing sugars are those that have a free aldehyde or ketone group and can reduce other compounds and get oxidised themselves.

The presence of reducing sugars like glucose can be detected by testing with Fehling’s solution. Glucose is an aldose hexose sugar with a free aldehyde group. It reduces the cupric $C{u}^{++}$ ions in the Fehling’s solution to cuprous $C{u}^{+}$ ions and the solution turns from blue to reddish brown.