Which of the following represents correct order of conductivity in solids ?

Options

A. `K_("metals") gt gt K_("insulators") lt K_("semiconductors")`
B. `K_("metals") lt lt K_("insulators") lt K_("semiconductors")`
C. `K_("metals") = K_("semiconductors") gt K_("insulators") = "zero"`
D. `K_("metals") lt K_("insulators") gt K_("semiconductors") ne "zero"`

Explanation

To determine the correct order of conductivity in solids, we need to analyze the conductivity of three types of materials: metals, insulators, and semiconductors.

### Step-by-Step Solution:

1. **Understanding Conductivity in Metals:**
- Metals have free electrons that allow them to conduct electricity efficiently.
- Therefore, metals exhibit **high conductivity**.

2. **Understanding Conductivity in Insulators:**
- Insulators lack free electrons, which means they do not allow electricity to pass through them.
- As a result, insulators have **very low conductivity**.

3. **Understanding Conductivity in Semiconductors:**
- Semiconductors have a conductivity that is temperature-dependent.
- At room temperature, semiconductors behave like insulators (low conductivity), but as the temperature increases, their conductivity increases as well.
- Thus, semiconductors have **moderate conductivity**, which is higher than insulators but lower than metals.

4. **Comparing Conductivities:**
- Based on the analysis:
- Metals: High conductivity
- Semiconductors: Moderate conductivity
- Insulators: Low conductivity

5. **Correct Order of Conductivity:**
- Therefore, the correct order of conductivity from highest to lowest is:
- **Metals > Semiconductors > Insulators**

### Final Answer:
The correct order of conductivity in solids is **Metals > Semiconductors > Insulators**.