Conductance measurements and be used to detect the end point of acid-base titrations. Which of the following plots correctly represents the end point of the titration of strong acid and a strong base?

Options

A.
B.
C.
D.

Explanation

To solve the question regarding the conductance measurements in acid-base titrations, we will analyze the behavior of conductance during the titration of a strong acid with a strong base.

### Step-by-Step Solution:

1. **Understanding Conductance in Titration**:
- Conductance is a measure of how well a solution can conduct electricity, which is influenced by the concentration of ions in the solution.
- In an acid-base titration, we start with a strong acid (which has a high concentration of H⁺ ions) and add a strong base (which provides OH⁻ ions).

2. **Initial Conductance**:
- Initially, the conductance of the solution is high due to the presence of a large number of H⁺ ions from the strong acid.

3. **Neutralization Reaction**:
- As we begin to add the strong base, the H⁺ ions react with OH⁻ ions to form water (H₂O). This neutralization reaction decreases the concentration of free ions in the solution.
- As the neutralization progresses, the conductance of the solution decreases because the number of H⁺ ions decreases.

4. **Point of Lowest Conductance**:
- The conductance will continue to decrease until we reach the equivalence point, where all the H⁺ ions have been neutralized by OH⁻ ions. At this point, the solution has the lowest conductance.

5. **Post Equivalence Point**:
- After the equivalence point, if we continue to add more base, the concentration of OH⁻ ions will increase. This increase in OH⁻ ions leads to an increase in conductance.
- Therefore, after reaching the lowest point, the conductance begins to rise again.

6. **Plot Representation**:
- The plot of conductance against the volume of titrant (strong base) added will show a decrease in conductance until the equivalence point is reached, followed by an increase in conductance after the equivalence point.
- The correct representation of this behavior is a graph that first decreases to a minimum and then rises, which corresponds to option A.

### Final Answer:
The correct plot that represents the end point of the titration of a strong acid and a strong base is **option A**.