Varun took a sample A and added dilute hydrochloric acid to it. A colourless, odourless gas X was evolved which turned lime water milky.
Identify sample A and the gas X evolved. Write a chemical equation to explain the reaction between Sample A and Hydrochloric acid. Why does the gas X turn lime water milky?

Explanation

To solve the question step by step, we will identify the sample A and gas X, write the chemical equation for the reaction, and explain why gas X turns lime water milky.

### Step 1: Identify Sample A and Gas X
- When dilute hydrochloric acid (HCl) is added to sample A, a colorless, odorless gas X is evolved that turns lime water milky.
- The gas that turns lime water milky is carbon dioxide (CO2).
- Therefore, sample A must be a metal carbonate, as metal carbonates react with acids to produce carbon dioxide.

**Sample A:** Metal Carbonate (e.g., Sodium Carbonate, Na2CO3)
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