A: Superconducting magnets are gainfully exploited in running magnetically levitated superfast trains.
R: Superconductors are diamagnetic substances which get repelled by strong external magnetic field.

Options

A. If both Assertion & Reason are the true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reson is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we need to analyze the assertion (A) and reason (R) provided:

**Assertion (A):** Superconducting magnets are gainfully exploited in running magnetically levitated superfast trains.
**Reason (R):** Superconductors are diamagnetic substances which get repelled by strong external magnetic fields.

### Step-by-Step Solution:

1. **Understanding the Assertion (A):**
- Superconducting magnets are indeed used in magnetically levitated (maglev) trains. These trains utilize the principles of magnetism to achieve levitation and propulsion.
- In maglev trains, superconducting magnets create a magnetic field that allows the train to float above the tracks, eliminating friction and allowing for high speeds.

2. **Explaining the Mechanism:**
- Maglev trains operate on the principle of magnetic levitation. They use superconducting magnets that are capable of producing strong magnetic fields.
- The train is levitated above the track, which is also equipped with magnets, allowing for both lift and propulsion.

3. **Understanding the Reason (R):**
- The reason states that superconductors are diamagnetic substances. This means they exhibit perfect diamagnetism, which allows them to be repelled by external magnetic fields.
- When a superconductor is placed in a magnetic field, it will expel the magnetic field lines (Meissner effect), leading to repulsion from the magnetic field.

4. **Connecting A and R:**
- The assertion is true because superconducting magnets are effectively used in maglev trains.
- The reason is also true as superconductors are indeed diamagnetic and are repelled by strong magnetic fields.
- The repulsion is essential for the levitation of the train, as it allows the train to float above the track.

5. **Conclusion:**
- Both the assertion (A) and the reason (R) are correct, and the reason correctly explains the assertion.

### Final Answer:
Both A and R are true, and R is the correct explanation of A.