Which of the following is/are true for an acid- base titration?

Options

A. Indicators catalyse the acid base reactions by releasing or accepting `H^(+)` ions.
B. Indicators do not significantly affect the pH of the solution to which they are added.
C. Acid - base reactions do not occur in absence of indicators
D. Indicators have different colours in dissociated and undissociated forms

Answer

To determine which statements are true regarding acid-base titrations, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Analyze Option A:**
- Statement: "Indicators catalyze the acid-base reactions by releasing or accepting H⁺ ions."
- **Explanation:** Indicators are substances that change color at a specific pH level to signal the endpoint of a titration. They do not participate in the reaction as catalysts; they merely indicate the endpoint. Therefore, this statement is **false**.

2. **Analyze Option B:**
- Statement: "Indicators do not significantly affect the pH of the solution to which they are added."
- **Explanation:** Indicators are typically weak acids or bases and are added in very small amounts during titrations. Their presence does not significantly alter the pH of the solution. Thus, this statement is **true**.

3. **Analyze Option C:**
- Statement: "Acid-base reactions do not occur in the absence of indicators."
- **Explanation:** Acid-base reactions can occur without indicators. Indicators are used to determine the endpoint of a titration but are not necessary for the reaction to take place. Therefore, this statement is **false**.

4. **Analyze Option D:**
- Statement: "Indicators have different colors in dissociated and undissociated forms."
- **Explanation:** Indicators exhibit different colors depending on their ionization state, which is influenced by the pH of the solution. This means that they will have different colors in their dissociated and undissociated forms. Thus, this statement is **true**.

### Conclusion:
Based on the analysis:
- **True Statements:** B and D
- **False Statements:** A and C

### Final Answer:
The true statements for an acid-base titration are:
- B: Indicators do not significantly affect the pH of the solution to which they are added.
- D: Indicators have different colors in dissociated and undissociated forms.

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