Relative density of an oil is `0.8`.Find the absolute density of oil in CGS and SI units.

Explanation

To find the absolute density of oil given its relative density, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Relative Density**:
Relative density (also known as specific gravity) is defined as the ratio of the density of a substance to the density of a reference substance, typically water at 4°C.

\[ \text{Relative Density} = \frac{\text{Density of Oil}}{\text{Density of Water}} \]

2. **Identify the Density of Water**:
The density of water is approximately \(1000 \, \text{kg/m}^3\) or \(1 \, \text{g/cm}^3\).

3. **Use the Given Relative Density**:
The relative density of the oil is given as \(0.8\).

4. **Calculate the Density of Oil in SI Units**:
Using the formula for relative density, we can rearrange it to find the density of oil:

\[ \text{Density of Oil} = \text{Relative Density} \times \text{Density of Water} \]

Substituting the values:

\[ \text{Density of Oil} = 0.8 \times 1000 \, \text{kg/m}^3 = 800 \, \text{kg/m}^3 \]

5. **Convert Density to CGS Units**:
To convert from SI units (kg/m³) to CGS units (g/cm³), we use the following conversion factors:
- \(1 \, \text{kg} = 1000 \, \text{g}\)
- \(1 \, \text{m}^3 = 10^6 \, \text{cm}^3\)

Therefore,

\[ 800 \, \text{kg/m}^3 = 800 \times 1000 \, \text{g/m}^3 = 800000 \, \text{g/m}^3 \]

Now, converting \(800000 \, \text{g/m}^3\) to g/cm³:

\[ 800000 \, \text{g/m}^3 = \frac{800000 \, \text{g}}{10^6 \, \text{cm}^3} = 0.8 \, \text{g/cm}^3 \]

### Final Answers:
- **Density of Oil in SI Units**: \(800 \, \text{kg/m}^3\)
- **Density of Oil in CGS Units**: \(0.8 \, \text{g/cm}^3\)