Correct Option
The correct option is (c) 1 and 3 only.
Explanation
Electrical conductivity refers to the ability of a material to allow the flow of electric charge. Materials are traditionally classified into conductors and insulators based on their resistance to this flow. However, this classification is relative rather than absolute, as conductivity depends on external conditions such as voltage and temperature.
Statement-wise Analysis
- Statement 1 is Correct: Insulators are materials with extremely high electrical resistance. They do not easily allow electric current to pass through them because their internal electric charges do not flow freely. Examples include rubber, plastic, and wood.
- Statement 2 is Incorrect: While air is generally an insulator, it is not a "perfect" insulator that never conducts. Under specific conditions, such as high voltage or strong electric fields (e.g., during lightning or sparking), air molecules become ionized and can conduct electricity. This phenomenon is known as dielectric breakdown.
- Statement 3 is Correct: Since most materials can conduct electricity under certain extreme conditions (like high voltage), the absolute distinction between "conductors" and "insulators" is technically imprecise. Therefore, in scientific contexts, it is often considered more appropriate to classify materials based on the degree of their conductivity-as "good conductors" (low resistance) and "poor conductors" (high resistance).
Key Takeaway: No material is a perfect insulator; even poor conductors like air can conduct electricity when subjected to sufficiently high electric fields (breakdown voltage).