Assertion (A): Gas bubbles are observed when sodium carbonate is added to dilute hydrochloric acid.
Reason (R): Carbon dioxide is given off in the reaction.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true.

Explanation

To solve the assertion and reason question, we will analyze both statements step by step.

### Step 1: Understanding the Assertion
The assertion states that "Gas bubbles are observed when sodium carbonate is added to dilute hydrochloric acid."
- When sodium carbonate (Na2CO3) is added to dilute hydrochloric acid (HCl), a chemical reaction occurs.

### Step 2: Writing the Reaction
The reaction between sodium carbonate and hydrochloric acid can be written as:
\[ \text{Na}_2\text{CO}_3 + 2\text{HCl} \rightarrow 2\text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 \uparrow \]
- Here, sodium chloride (NaCl) is formed as a salt, water (H2O) is produced, and carbon dioxide (CO2) gas is released.

### Step 3: Observing Gas Bubbles
- The production of carbon dioxide gas is what causes the gas bubbles to form when the reaction takes place. This confirms the assertion that gas bubbles are observed.

### Step 4: Understanding the Reason
The reason states that "Carbon dioxide is given off in the reaction."
- From the reaction we wrote, we see that carbon dioxide (CO2) is indeed produced as one of the products of the reaction.

### Step 5: Conclusion
Both the assertion and the reason are true. Furthermore, the reason correctly explains the assertion, as the gas bubbles observed are due to the evolution of carbon dioxide.

### Final Answer
- Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A. Therefore, the correct answer is Option 1.

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