Which of the following statements are correct ?
(i) An electric circuit must be opened for current to flow through it.
(ii) A dry cell converts electrical energy into chemical energy.
(iii) Electric current always flows from positive to the negative terminal of the cell through the circuit.
(iv) Pure water does not conduct electricity.

Options

A. (i) and (ii) only
B. (iii) and (iv) only
C. (i), (ii) and (iii) only
D. (i), (iii) and (iv) only

Explanation

To determine which of the statements are correct, let's analyze each one step by step:

1. **Statement (i): An electric circuit must be opened for current to flow through it.**
- This statement is incorrect. For current to flow, an electric circuit must be **closed**. A closed circuit allows the flow of electric current, while an open circuit does not.

2. **Statement (ii): A dry cell converts electrical energy into chemical energy.**
- This statement is also incorrect. A dry cell actually converts **chemical energy into electrical energy**. When the chemicals inside the cell react, they produce electrical energy that can be used to power devices.

3. **Statement (iii): Electric current always flows from positive to the negative terminal of the cell through the circuit.**
- This statement is correct. By convention, electric current is considered to flow from the positive terminal to the negative terminal. This is known as conventional current flow.

4. **Statement (iv): Pure water does not conduct electricity.**
- This statement is generally considered correct. Pure water (distilled water) has very few ions and does not conduct electricity well. However, impurities in water can allow it to conduct electricity.

Now, summarizing the analysis:
- Statement (i) is incorrect.
- Statement (ii) is incorrect.
- Statement (iii) is correct.
- Statement (iv) is correct.

**Final Answer: Statements (iii) and (iv) are correct.**