Substances with different densities can be separated by

Options

A. filtration
B. decantation
C. centrifugation
D. winnowing

Answer

To answer the question, "Substances with different densities can be separated by," we will analyze the methods of separation provided and determine which one is appropriate for substances with different densities.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for a method to separate substances based on their different densities.

2. **Evaluate Filtration**:
- Filtration is a process used to separate solids from liquids.
- It involves using a filter medium (like filter paper) to allow liquids to pass while retaining solid particles.
- **Conclusion**: This method does not specifically separate substances based on density.

3. **Evaluate Decantation**:
- Decantation is used to separate mixtures of immiscible liquids or a liquid and a solid.
- It works by allowing the denser substance to settle at the bottom, enabling the lighter liquid to be poured off.
- **Conclusion**: While it can separate based on density, it is not the most effective method for substances with significantly different densities.

4. **Evaluate Centrifugation**:
- Centrifugation is a technique that separates particles from a solution based on size, shape, density, and viscosity.
- It involves spinning the mixture rapidly, causing denser particles to move outward while lighter ones remain closer to the center.
- **Conclusion**: This method is specifically designed to separate substances based on their densities and is effective for substances with different densities.

5. **Evaluate Winnowing**:
- Winnowing is an agricultural method used to separate heavier grains from lighter husk using wind.
- It relies on the difference in weight rather than density in a liquid medium.
- **Conclusion**: This method is not applicable for separating substances in a laboratory context based on density.

6. **Final Answer**: The best method for separating substances with different densities is **centrifugation**.