A solution which resists the cahnge in its pH value on addition of some amount of acid or base is called

Options

A. A colloid
B. A crystalloid
C. A buffer
D. An indicator

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a type of solution that resists changes in pH when small amounts of acid or base are added.

2. **Definition of Buffer Solutions**: The solution that meets this criterion is known as a "buffer solution." Buffer solutions are designed to maintain a relatively constant pH despite the addition of acids or bases.

3. **Types of Buffer Solutions**:
- **Acidic Buffer**: This type of buffer is made from a weak acid and its conjugate base (which is typically a salt formed from a weak acid and a strong base). For example, a mixture of acetic acid (weak acid) and sodium acetate (salt).
- **Basic Buffer**: This type of buffer is formed from a weak base and its conjugate acid (which is typically a salt formed from a weak base and a strong acid). An example would be ammonia (weak base) and ammonium chloride (salt).

4. **Function of Buffer Solutions**: When an acid is added to an acidic buffer, the weak acid in the buffer reacts with the added acid to minimize the change in pH. Similarly, when a base is added, the conjugate base reacts with the added base to resist changes in pH.

5. **Conclusion**: Therefore, the answer to the question is that a solution which resists the change in its pH value on the addition of some amount of acid or base is called a "buffer solution."

**Final Answer**: Buffer solution.

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