Which of the following is not a property of acids?

Options

A. all acids have a sour taste
B. acids turn blue litmus red
C. acids turn red litmus blue
D. all acids form `H^+` ions in water

Answer

To determine which of the following is not a property of acids, we will evaluate each option provided in the question.

### Step-by-Step Solution:

1. **Identify the properties of acids:**
- Acids are known to have a sour taste.
- Acids turn blue litmus paper red.
- Acids release hydrogen ions (H⁺) when dissolved in water.

2. **Evaluate each option:**
- **Option 1:** "All acids have a sour taste."
- This is a true property of acids. For example, lemon juice is acidic and has a sour taste.

- **Option 2:** "Acid turns blue litmus to red."
- This is also a true property of acids. When an acid is present, blue litmus paper changes to red.

- **Option 3:** "Acid turns red litmus to blue."
- This statement is incorrect. This property is characteristic of bases, not acids. Acids do not turn red litmus paper blue; they turn blue litmus paper red.

- **Option 4:** "All acids form H⁺ ions in water."
- This is a true property of acids. When acids dissolve in water, they dissociate to produce H⁺ ions.

3. **Conclusion:**
- The statement that is not a property of acids is **Option 3: "Acid turns red litmus to blue."** This is a property of bases.

### Final Answer:
The correct answer is **Option 3**.

---