Which of the following substance will sink in water?

Options

A. Plank made up of wood
B. Plastic bucket full of water
C. A small sheet of glass
D. Plastic soap case with soap In it

Answer

To determine which substance will sink in water, we need to analyze the density of each substance in relation to water. The key principle here is that substances with a density greater than that of water (which is approximately 1 g/cm³) will sink, while those with a density less than that will float.

### Step-by-Step Solution:

1. **Identify the substances**: The substances given in the question are:
- Wooden plank
- Plastic bucket full of water
- Small sheet of glass
- Plastic soap case with soap in it

2. **Analyze the wooden plank**:
- Wood typically has a density less than that of water, which means it will float.
- **Conclusion**: The wooden plank will **not sink**.

3. **Analyze the plastic bucket full of water**:
- A plastic bucket itself is generally less dense than water, but if it is full of water, the overall density of the bucket (including the water) can be close to that of water. However, since it is a plastic bucket, it will likely float.
- **Conclusion**: The plastic bucket will **not sink**.

4. **Analyze the small sheet of glass**:
- Glass has a density greater than that of water, which means it will sink when placed in water.
- **Conclusion**: The small sheet of glass will **sink**.

5. **Analyze the plastic soap case with soap in it**:
- The plastic itself is less dense than water, but if it contains soap, the overall density may increase depending on the amount of soap. If the soap case is heavy enough, it can sink.
- **Conclusion**: The plastic soap case with soap in it will likely **sink**.

6. **Final determination**:
- Based on the analysis, the substances that will sink in water are:
- Small sheet of glass
- Plastic soap case with soap in it

### Answer:
The substances that will sink in water are the **small sheet of glass** and the **plastic soap case with soap in it**.