The percentage of ozone in ozonised oxygen is about `80 %`.

Explanation

To determine whether the statement "The percentage of ozone in ozonised oxygen is about 80%" is true or false, we can analyze the formation of ozone and its concentration in ozonised oxygen.

### Step-by-Step Solution:

1. **Understanding Ozonised Oxygen**:
- Ozonised oxygen is produced when oxygen gas (O₂) undergoes silent electric discharge. This process converts some of the oxygen molecules into ozone (O₃).

2. **Chemical Reaction**:
- The reaction can be represented as:
\[ 3 O_2 \xrightarrow{\text{electric discharge}} 2 O_3 \]
- This indicates that for every three molecules of oxygen, two molecules of ozone are formed.

3. **Calculating the Percentage of Ozone**:
- In ozonised oxygen, the total amount of gas consists of both O₂ and O₃. However, the concentration of ozone is relatively low compared to the total volume of gas.
- Typically, the concentration of ozone in ozonised oxygen is around 10%, not 80%.

4. **Conclusion**:
- Since the percentage of ozone in ozonised oxygen is approximately 10%, the statement claiming it is about 80% is false.

### Final Answer:
The statement "The percentage of ozone in ozonised oxygen is about 80%" is **False**.

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