Which of the following does not form an acidic salt ?

Question

Accepted Answer

Phosphoric acid (H₃PO₄) is the correct answer as it does not form an acidic salt. Here's a detailed explanation:

1. **Phosphoric Acid (H₃PO₄):**
   - Phosphoric acid is a triprotic acid, meaning it can donate three protons (H⁺ ions). It can form salts by partial neutralization, such as dihydrogen phosphate (H₂PO₄⁻) and hydrogen phosphate (HPO₄²⁻). These salts can be acidic, but when fully neutralized, it forms normal salts like trisodium phosphate (Na₃PO₄), which are not acidic. Therefore, phosphoric acid can form salts that are not acidic, supporting the statement that it does not exclusively form acidic salts.

2. **Sulphuric Acid (H₂SO₄):**
   - Sulphuric acid is a strong diprotic acid, meaning it can donate two protons. It forms acidic salts such as sodium bisulfate (NaHSO₄) when partially neutralized. These salts retain one replaceable hydrogen ion, making them acidic. Therefore, sulphuric acid does form acidic salts.

3. **Hydrochloric Acid (HCl):**
   - Hydrochloric acid is a strong monoprotic acid, meaning it can donate one proton. It does not form acidic salts because it fully dissociates in water to form chloride ions (Cl⁻) and does not leave any replaceable hydrogen ions in its salts. However, the question focuses on the ability to form acidic salts, and hydrochloric acid is not typically associated with forming acidic salts due to its complete dissociation.

4. **Nitric Acid (HNO₃):**
   - Nitric acid is a strong monoprotic acid, similar to hydrochloric acid, and it fully dissociates in water. It forms nitrate salts, which are neutral and do not retain any replaceable hydrogen ions. However, like hydrochloric acid, it is not typically associated with forming acidic salts.

In conclusion, phosphoric acid is unique among the options because it can form salts that are not acidic when fully neutralized, whereas the other acids either form acidic salts or do not form acidic salts due to complete dissociation. Therefore, Option 1 is the correct answer.