Find the number of ion which are identified by dil. HCI from the following :
(i) `CO_(3)^(2-) `(ii) `SO_(3)^(2-)` (iii)`SO_(4)^(2-)`

Explanation

To find the number of ions that can be identified by dilute HCl from the given ions: \( \text{CO}_3^{2-} \) (carbonate), \( \text{SO}_3^{2-} \) (sulphite), and \( \text{SO}_4^{2-} \) (sulphate), we will analyze each ion's reaction with dilute HCl.

### Step 1: Identify the reaction of Carbonate Ion (\( \text{CO}_3^{2-} \))
- When carbonate ions react with dilute HCl, they produce carbon dioxide gas (\( \text{CO}_2 \)) and water. The reaction can be represented as:
\[ \text{CO}_3^{2-} + 2 \text{HCl} \rightarrow \text{CO}_2 \uparrow + \text{H}_2\text{O} + 2 \text{Cl}^- \]
- The evolution of carbon dioxide gas can be observed as brisk effervescence, and it can be confirmed by passing the gas through lime water, which turns milky due to the formation of calcium carbonate.

### Step 2: Identify the reaction of Sulphite Ion (\( \text{SO}_3^{2-} \))
- When sulphite ions react with dilute HCl, they produce sulfur dioxide gas (\( \text{SO}_2 \)). The reaction is as follows:
\[ \text{SO}_3^{2-} + 2 \text{HCl} \rightarrow \text{SO}_2 \uparrow + \text{H}_2\text{O} + 2 \text{Cl}^- \]
- The sulfur dioxide gas is colorless and has a characteristic suffocating smell. It can also be tested by its ability to reduce potassium dichromate from orange to green.

### Step 3: Identify the reaction of Sulphate Ion (\( \text{SO}_4^{2-} \))
- Sulphate ions do not react with dilute HCl to produce any gas. The reaction does not lead to the identification of sulphate ions using dilute HCl. Therefore, no observable reaction occurs.

### Conclusion
From the analysis:
- Carbonate ion (\( \text{CO}_3^{2-} \)) can be identified.
- Sulphite ion (\( \text{SO}_3^{2-} \)) can also be identified.
- Sulphate ion (\( \text{SO}_4^{2-} \)) cannot be identified using dilute HCl.

Thus, the total number of ions that can be identified by dilute HCl is **2** (carbonate and sulphite).

### Final Answer
The number of ions identified by dilute HCl is **2**.

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