Which of the following are insulators ?

Options

A. Brass , gold , steel
B. Tap water , human body , silver
C. Moist air , human body
D. Pure water , air mica

Explanation

To determine which of the given options contains insulators, we need to understand what insulators are. Insulators are materials that do not allow electric current to flow through them, while conductors allow electric current to pass.

### Step-by-Step Solution:

1. **Identify the Definition of Insulators**:
- Insulators are materials that do not conduct electricity. Examples include rubber, glass, and certain types of plastics.

2. **Analyze Each Option**:
- **Option 1: Brass, Gold, and Steel**
- All these materials are metals and are known to be good conductors of electricity. Therefore, they are not insulators.

- **Option 2: Tap Water, Human Body, and Silver**
- Tap water contains impurities and can conduct electricity. The human body is also a conductor due to the presence of water and electrolytes. Silver is a metal and a good conductor. Hence, this option does not contain insulators.

- **Option 3: Moist Air and Human Body**
- Moist air can conduct electricity due to the presence of water vapor. The human body, as mentioned earlier, is also a conductor. Thus, this option does not contain insulators.

- **Option 4: Pure Water, Air, and Mica**
- Pure water is generally considered an insulator, especially when it is free of impurities. Air is also an insulator under normal conditions. Mica is a well-known insulator used in electrical applications. Therefore, this option contains insulators.

3. **Conclusion**:
- The correct answer is **Option 4: Pure Water, Air, and Mica**, as these materials do not allow electric current to flow through them.

### Final Answer:
**Option 4: Pure Water, Air, and Mica are insulators.**

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