Some of the molecular solid upon heating produces small amount of electricity, hence solid is

Options

A. Piezoelectric
B. Pyroelectric
C. Ferrielectric
D. Ferroelectric

Answer

To solve the question regarding which type of molecular solid produces a small amount of electricity upon heating, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the type of molecular solid that generates electricity when heated. We have four options to consider: piezoelectric, pyroelectric, ferrielectric, and ferroelectric.

2. **Analyze Each Option**:
- **Option A: Piezoelectric**: These materials generate an electric charge in response to applied mechanical stress. They do not produce electricity solely from heating.
- **Option B: Pyroelectric**: These materials generate an electric charge when they are heated or cooled. This matches the requirement of the question.
- **Option C: Ferrielectric**: This term is not commonly used in the context of solid-state physics. There is no known class of materials categorized as ferrielectric.
- **Option D: Ferroelectric**: These materials have a spontaneous electric polarization that can be reversed by applying an external electric field. They do not specifically produce electricity from heating.

3. **Identify the Correct Answer**: Based on the analysis, the only option that describes a solid that produces electricity upon heating is **Option B: Pyroelectric**.

4. **Conclusion**: The correct answer to the question is **pyroelectric**.

### Final Answer:
**Option B: Pyroelectric**

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