Which of the following statements are correct?
I. Human body is a good conductor of electricity.
II. The air gap surrounding an electric circuit acts as a conductor
III. Silver conducts electricity better than copper:
IV. When electricity lights up a bulb, no heat is produced.

Options

A. I and III only B.
B. I and II only
C. III and IV only
D. II, III and IV only

Answer

To determine which statements are correct, let's analyze each statement one by one:

### Step 1: Analyze Statement I
**Statement I:** Human body is a good conductor of electricity.
- The human body contains ions (like sodium and potassium) that allow the flow of electric current. Therefore, this statement is **correct**.

### Step 2: Analyze Statement II
**Statement II:** The air gap surrounding an electric circuit acts as a conductor.
- Air is generally considered an insulator, meaning it does not conduct electricity well. Therefore, this statement is **incorrect**.

### Step 3: Analyze Statement III
**Statement III:** Silver conducts electricity better than copper.
- Silver is known to be the best conductor of electricity, even better than copper. Therefore, this statement is **correct**.

### Step 4: Analyze Statement IV
**Statement IV:** When electricity lights up a bulb, no heat is produced.
- When electricity passes through a bulb, it typically generates heat due to the resistance of the filament (often made of tungsten). Therefore, this statement is **incorrect**.

### Conclusion
Based on the analysis:
- Statement I is **correct**.
- Statement II is **incorrect**.
- Statement III is **correct**.
- Statement IV is **incorrect**.

Thus, the correct statements are I and III.