Which of the following is the smallest unit ?

Options

A. Micron
B. Fermi
C. Millimetre
D. Kilometre

Answer

To determine which of the following units is the smallest, we will compare the values of each unit given in the options. The options are:

1. Micro
2. Fermi
3. Millimeter
4. Kilometer

**Step 1: Understand the value of each unit.**

- **Micro (µ)**: This unit is equal to \(10^{-6}\).
- **Fermi (fm)**: This unit is equal to \(10^{-15}\).
- **Millimeter (mm)**: This unit is equal to \(10^{-3}\).
- **Kilometer (km)**: This unit is equal to \(10^{3}\).

**Step 2: Compare the values.**

Now we will compare the powers of ten for each unit:

- Micro: \(10^{-6}\)
- Fermi: \(10^{-15}\)
- Millimeter: \(10^{-3}\)
- Kilometer: \(10^{3}\)

**Step 3: Identify the smallest value.**

Among the values:
- \(10^{-15}\) (Fermi) is smaller than \(10^{-6}\) (Micro), \(10^{-3}\) (Millimeter), and \(10^{3}\) (Kilometer).

**Step 4: Conclusion.**

Thus, the smallest unit among the given options is the **Fermi**.

**Final Answer: Option 2: Fermi**

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