Assertion (A): Aqueous solution of `Na_(2)CO_(3)` is alkaline in nature.
Reason (R ): when dissolved in water, `Na_(2)CO_(3)` undergoes anionic hydrolysis.

Options

A. If both (A) and (R ) are correct and (R ) is the correct explanation of (A).
B. If both (A) and (R ) are correct, but (R ) is not the correct explanation of (A).
C. If (A) is correct, but (R ) is incorrect.
D. If (A) is incorrect, but (R ) is correct.

Answer

To solve the assertion and reason question regarding sodium carbonate (Na₂CO₃), we will break down the components step by step.

### Step 1: Understand the Assertion
The assertion states that an aqueous solution of Na₂CO₃ is alkaline in nature. This means that when Na₂CO₃ is dissolved in water, the resulting solution has a pH greater than 7, indicating that it is basic.

**Hint:** Recall that alkaline solutions contain hydroxide ions (OH⁻).

### Step 2: Analyze the Composition of Na₂CO₃
Sodium carbonate (Na₂CO₃) is composed of sodium ions (Na⁺) and carbonate ions (CO₃²⁻). Sodium ions come from a strong base (NaOH), while carbonate ions come from a weak acid (H₂CO₃).

**Hint:** Identify the strength of the acid and base that form the salt.

### Step 3: Hydrolysis of Na₂CO₃
When Na₂CO₃ is dissolved in water, it dissociates into Na⁺ and CO₃²⁻ ions. The carbonate ion (CO₃²⁻) can undergo hydrolysis, which means it reacts with water.

**Hint:** Remember that hydrolysis involves a reaction with water that can change the pH of the solution.

### Step 4: Reaction of Carbonate Ion with Water
The carbonate ion reacts with water as follows:
\[ \text{CO}_3^{2-} + \text{H}_2\text{O} \rightleftharpoons \text{HCO}_3^{-} + \text{OH}^- \]
This reaction produces bicarbonate ions (HCO₃⁻) and hydroxide ions (OH⁻). The presence of OH⁻ ions increases the pH of the solution, making it alkaline.

**Hint:** Focus on the production of hydroxide ions during the hydrolysis process.

### Step 5: Conclusion on Assertion and Reason
Since the hydrolysis of the carbonate ion leads to the formation of hydroxide ions, the assertion that an aqueous solution of Na₂CO₃ is alkaline is correct. The reason provided, that Na₂CO₃ undergoes anionic hydrolysis, is also correct and explains why the solution is alkaline.

**Hint:** Confirm that both the assertion and reason are true and that the reason correctly explains the assertion.

### Final Answer
Both the assertion (A) and reason (R) are true, and the reason is the correct explanation of the assertion. Therefore, the answer is A.