Bases turn red litmus blue and acids turn blue litmus red.
A student tested a liquid with a red litmus paper and it stayed red with no change this shows that the liquid

Options

A. must be pure water
B. must be an acid
C. is not a base
D. is neither a base nor an acid

Explanation

To solve the question, we need to analyze the behavior of the liquid tested with red litmus paper. Here’s a step-by-step breakdown:

### Step 1: Understand the properties of litmus paper
Litmus paper is a pH indicator that changes color in response to acidic or basic solutions. Red litmus paper turns blue in the presence of a base, while blue litmus paper turns red in the presence of an acid.

### Step 2: Analyze the test result
The student tested a liquid with red litmus paper, and the paper remained red with no change. This indicates that the liquid did not have basic properties.

### Step 3: Determine the implications of the result
Since the red litmus paper did not change color, we can conclude that the liquid is either neutral or acidic. If it were a base, the red litmus paper would have turned blue.

### Step 4: Consider the nature of the liquid
1. **Neutral Solution**: A neutral solution, like pure water (pH 7), will not change the color of either red or blue litmus paper.
2. **Acidic Solution**: An acidic solution will also not change the color of red litmus paper, as it remains red.

### Step 5: Conclusion
The liquid tested could be:
- Pure water (neutral)
- An acid (since it does not change the red litmus paper)

Thus, the liquid is not a base, and it can either be pure water or an acid.

### Final Answer
The liquid is either pure water or an acid.

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