The correct option is (c).
Explanation
Materials are classified based on their ability to allow electric current to pass through them. While traditionally categorized as conductors and insulators, a more precise scientific distinction is often made between "good conductors" and "poor conductors," as most insulators can conduct electricity under extreme conditions.
Statement-wise Analysis:
- Statement 1 is Incorrect. Under normal conditions (standard temperature and pressure), air does not allow electric current to pass through it easily. It acts as an electrical insulator, preventing the leakage of current from open wires or switches.
- Statement 2 is Correct. During phenomena like lightning, the electric potential difference between clouds and the ground (or between clouds) becomes extremely high. This high electric field causes the dielectric breakdown of air, ionizing it and turning it into plasma. In this state, air conducts massive amounts of electric current.
- Statement 3 is Correct. Since air can conduct electricity under specific conditions (like lightning), it is technically inaccurate to label it as a perfect insulator. In physics, it is preferable to classify materials as good conductors (like copper) and poor conductors (like air and rubber) rather than using the absolute term "insulator," which implies no conduction is ever possible.
Key Takeaway:
Air is a poor conductor of electricity under normal conditions but undergoes dielectric breakdown to become a conductor under high electric fields, such as during lightning.