Question

Among the following the least unit for length is

• A. parsec
• B. nanometer
• C. fermi
• D. angstrom

Hint:

When comparing different units of length, remember that the prefix tells you how many zeros are involved in the conversion. For example, a nanometer (nm) is \(10^{-9}\) meters, while a fermi (fm) is \(10^{-15}\) meters, which makes it the smallest unit in this list.

Answer 1

The Correct Option is C

The units given are all used to measure length but vary greatly in magnitude:
- A parsec is a very large unit used to measure astronomical distances, equal to approximately 3.26 light years.
- A nanometer is 10^{-9} meters, often used to measure atomic and molecular distances.
- A fermi (also known as a femtometer) is \(10^{-15}\) meters, the smallest unit listed here, used to measure nuclear sizes.
- An angstrom is \(10^{-10}\) meters, used to measure atomic dimensions, but larger than a fermi.
Among these, the fermi is the smallest unit for length. Therefore, the correct answer is option (3), fermi.

Answer 2

Step 1: List the typical small units of length
- Micrometer: \(10^{-6}\) m
- Nanometer: \(10^{-9}\) m
- Angstrom: \(10^{-10}\) m
- Fermi: \(10^{-15}\) m

Step 2: Identify the smallest unit
Among these, fermi is the smallest unit.

Final Answer: fermi