Which of the following is not a unit of time?

Options

A. second
B. minute
C. hour
D. light year

Answer

To determine which of the following is not a unit of time, we will analyze each option provided:

1. **Second**:
- The second is a widely recognized unit of time. It is the base unit of time in the International System of Units (SI). Therefore, this option is a unit of time.
- **Conclusion**: This option is incorrect as it is a unit of time.

2. **Minute**:
- A minute is defined as 60 seconds. It is also a standard unit of time. Hence, this option is also a unit of time.
- **Conclusion**: This option is incorrect as it is a unit of time.

3. **Hour**:
- An hour consists of 60 minutes, which translates to 3600 seconds. It is another standard unit of time. Thus, this option is also a unit of time.
- **Conclusion**: This option is incorrect as it is a unit of time.

4. **Light Year**:
- A light year is defined as the distance that light travels in one year. Although it contains the word "year," it is not a unit of time; rather, it is a unit of distance. Specifically, 1 light year is approximately equal to 9.46 x 10^15 meters.
- **Conclusion**: This option is correct as it is not a unit of time.

**Final Answer**: The option that is not a unit of time is **Light Year**.

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