Consider the following statements
I. Heavy water is radioactive in nature.
II. Heavy water is formed by electrolysis of normal water,
III. Heavy water is not harmful for organisms.
Which of the statement(s) given above is/are incorrect?

Options

A. Only II
B. I and II
C. I, II and III
D. III and I

Explanation

To determine which of the statements regarding heavy water (D2O) are incorrect, let's analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** Heavy water is radioactive in nature.

- **Explanation:** Heavy water is composed of deuterium (D), which is a stable isotope of hydrogen, and oxygen. Heavy water itself is not radioactive. Therefore, this statement is **incorrect**.

### Step 2: Analyze Statement II
**Statement II:** Heavy water is formed by electrolysis of normal water.

- **Explanation:** Heavy water can indeed be produced through the electrolysis of normal water (H2O). During electrolysis, the lighter hydrogen isotopes are preferentially separated, allowing for the concentration of deuterium in the remaining water. Thus, this statement is **correct**.

### Step 3: Analyze Statement III
**Statement III:** Heavy water is not harmful for organisms.

- **Explanation:** While heavy water is not immediately toxic, it can be harmful to organisms in large quantities. Organisms rely on normal water for biological processes, and replacing it with heavy water can disrupt cellular functions. Thus, this statement is generally considered **incorrect**.

### Conclusion
Based on the analysis:
- Statement I is incorrect.
- Statement II is correct.
- Statement III is incorrect.

### Final Answer
The incorrect statements are I and III.

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