Which of the following gives the correct increasing order of acid strength?

Options

A. water `lt` acetic acid `lt` hydrochloric acid
B. water `lt` hydrochloric acid `lt` acetic acid
C. Acetic acid `lt` water `lt` hydrochloric acid
D. Hydrochloric acid `lt` water `lt` acetic acid

Explanation

To determine the correct increasing order of acid strength among the given substances (HCl, water, and acetic acid), we need to analyze how each substance behaves in water in terms of its ability to donate protons (H⁺ ions).

### Step-by-Step Solution:

1. **Understanding Acids**:
- An acid is defined as a substance that can donate protons (H⁺ ions) when dissolved in water. The strength of an acid is determined by its ability to dissociate and release H⁺ ions.

2. **Analyzing HCl**:
- Hydrochloric acid (HCl) is a strong acid. It completely dissociates in water to produce H⁺ and Cl⁻ ions. This means it readily donates protons, making it a strong acid.

3. **Analyzing Acetic Acid**:
- Acetic acid (CH₃COOH) is a weak acid. It only partially dissociates in water, meaning that not all acetic acid molecules release H⁺ ions. Therefore, it is less effective at donating protons compared to strong acids like HCl.

4. **Analyzing Water**:
- Water (H₂O) is neutral and does not act as an acid in the traditional sense. While it can participate in acid-base reactions, it does not donate protons in the same manner as HCl or acetic acid. Thus, it has the lowest acidity.

5. **Establishing the Order**:
- Based on the above analysis, we can rank the substances in terms of increasing acid strength:
- Water (least acidic)
- Acetic Acid (weak acid)
- HCl (strong acid)

6. **Final Order**:
- The correct increasing order of acid strength is: **Water < Acetic Acid < HCl**.