Question

Light year is the unit of the following physical quantity

• A. Time
• B. Distance
• C. Mass
• D. None

Answer 1

The correct option is B

Distance

Explanation for the correct option

Option (B)

1. Light-year is the unit of length to measure large distances (astronomical distances).
2. The total distance travelled by light in 1 year is called 1 light year.
3. 1 light-year = 9.46 × 10¹² km.

Explanation for the incorrect options

1. The second (sec) is the unit of time.
2. A kg is the unit of mass.

Therefore, Light year is the unit of distance. So, option (B) is correct.