…………… is used for measurig long time intervals of the order of ……….. Sec.

Answer

To answer the question, we need to identify the appropriate method for measuring long time intervals and specify the order of seconds involved.

### Step-by-Step Solution:

1. **Identify the Measurement Method**:
- The method used for measuring long time intervals is **radioactive dating**. This technique is based on the decay of radioactive isotopes and is commonly used in geology and archaeology to determine the age of materials.

2. **Determine the Time Interval**:
- Radioactive dating can measure time intervals on the order of **10^17 seconds**. This is a very large time scale, suitable for dating geological formations and ancient artifacts.

3. **Fill in the Blanks**:
- Therefore, the complete answer to the question is:
- **Radioactive dating** is used for measuring long time intervals of the order of **10^17 seconds**.

### Final Answer:
**Radioactive dating is used for measuring long time intervals of the order of 10^17 seconds.**

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