Which of the following statement about a maglev train is/are not true?
(i) A maglev train does not have wheels.
(ii) Magnets in the track and on the bottom of the train repel to lift up the train above its track.
(iii) Magnetic forces of attraction are used to reduce friction.
(iv) Gravity does not act on a moving maglev train.

Options

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

Explanation

To determine which statements about a maglev train are not true, let's analyze each statement one by one:

1. **Statement (i): A maglev train does not have wheels.**
- This statement is **true**. Maglev trains operate on magnetic levitation, meaning they do not have wheels and instead float above the track.

2. **Statement (ii): Magnets in the track and on the bottom of the train repel to lift up the train above its track.**
- This statement is **true**. The magnets on the train and the track repel each other, creating a lifting force that allows the train to levitate above the track.

3. **Statement (iii): Magnetic forces of attraction are used to reduce friction.**
- This statement is **not true**. Maglev trains use magnetic forces of **repulsion** to levitate, and because they do not touch the track, there is minimal friction. Therefore, this statement is incorrect.

4. **Statement (iv): Gravity does not act on a moving maglev train.**
- This statement is **not true**. Gravity always acts on all objects, including a maglev train, regardless of its motion. Therefore, this statement is also incorrect.

### Conclusion:
The statements that are **not true** about a maglev train are:
- Statement (iii): Magnetic forces of attraction are used to reduce friction.
- Statement (iv): Gravity does not act on a moving maglev train.

### Final Answer:
The statements that are not true are **(iii) and (iv)**.

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