Glucose on Fehling's test gives .....

Options

A. no reaction
B. silver mirror
C. red precipitate
D. pungent gas

Answer

To solve the question "Glucose on Fehling's test gives .....", we will follow these steps:

### Step 1: Understand Fehling's Test
Fehling's test is a chemical test used to differentiate between reducing and non-reducing sugars. It involves the use of two solutions, known as Fehling's solution A and B.

### Step 2: Identify the Components of Fehling's Solution
- **Fehling's Solution A** contains copper(II) sulfate (CuSO₄), which is blue in color.
- **Fehling's Solution B** contains a mixture of potassium sodium tartrate and sodium hydroxide.

### Step 3: Prepare Fehling's Solution
To perform the test, equal volumes of Fehling's Solution A and B are mixed together to form the final Fehling's solution, which retains the blue color due to the presence of Cu²⁺ ions.

### Step 4: Perform the Test with Glucose
When glucose, a reducing sugar, is added to the Fehling's solution and heated, it reduces the Cu²⁺ ions to Cu⁺ ions. This reduction leads to the formation of copper(I) oxide (Cu₂O), which precipitates out of the solution.

### Step 5: Observe the Result
The formation of a red precipitate indicates a positive result for the Fehling's test. Thus, glucose will give a positive Fehling's test.

### Final Answer:
Glucose on Fehling's test gives a red precipitate.

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