pH scale was introduced by :

Options

A. Arrhenius
B. Sorensen
C. Lewis
D. Lowry

Explanation

To solve the question "pH scale was introduced by:", we need to identify the correct scientist from the given options: Arrhenius, Sorensen, Lewis, and Lowry.

### Step-by-Step Solution:

1. **Understanding the pH Scale**: The pH scale is a measure of how acidic or basic a solution is. It is based on the concentration of hydrogen ions (H⁺) in a solution.

2. **Identifying the Scientist**: The pH scale was introduced in the year 1909. We need to recall or research which scientist was responsible for this introduction.

3. **Researching the Options**:
- **Arrhenius**: Known for his theory of acids and bases but did not introduce the pH scale.
- **Lewis**: Known for the Lewis acid-base theory, not related to the pH scale.
- **Lowry**: Known for the Brønsted-Lowry theory of acids and bases, but not for introducing the pH scale.
- **Sorensen**: Søren Sørensen is the scientist who introduced the pH scale in 1909.

4. **Conclusion**: Based on the information gathered, the correct answer is **Søren Sørensen**.

### Final Answer:
The pH scale was introduced by **Søren Sørensen** in 1909.

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