`Na_(2)CO_(3)+H_(2)O+CO_(2)rarr(A).` White crystalline powder (A) on reaction with phenolphthalein gives

Options

A. Pink colour
B. Yellow colour
C. Orange colour
D. No colour

Answer

To solve the question regarding the reaction of sodium carbonate (Na₂CO₃) with water (H₂O) and carbon dioxide (CO₂), let’s break it down step by step:

### Step 1: Identify the Reaction
When sodium carbonate reacts with water and carbon dioxide, it forms sodium bicarbonate (NaHCO₃). The balanced chemical equation for this reaction is:

\[ \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2 \rightarrow 2 \text{NaHCO}_3 \]

### Step 2: Identify the Product (A)
The product formed (A) in this reaction is sodium bicarbonate (NaHCO₃), which is a white crystalline powder.

### Step 3: Understand the Properties of Sodium Bicarbonate
Sodium bicarbonate is known to be a weak base. When dissolved in water, it can affect the pH of the solution.

### Step 4: Reaction with Phenolphthalein
Phenolphthalein is a pH indicator that changes color in response to the acidity or basicity of a solution. It is colorless in acidic solutions and turns pink in basic solutions.

- Since sodium bicarbonate is a weak base, when it is dissolved in water, the solution will be slightly basic.

### Step 5: Conclusion on Color Change
When phenolphthalein is added to a solution of sodium bicarbonate, it will turn pink, indicating the presence of a weakly basic solution.

### Final Answer
The white crystalline powder (A) on reaction with phenolphthalein gives a **pink color**.

---