Question

Which of the following is unit of
length
1. lunar month
2. candela
3. kelvin
4. light year​

Answer 1

Explanation:

light year is the correct answer

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Answer 2

Light year is the unit of length.

To properly understand this answer, we have to know more about units.

Unit :

• Unit can be defined as, "the quantity of the constant magnitude which is used as a reference for measuring magnitudes of some other quantities having identical nature."
• There are various systems of unit. (Eg. SI, CGS)
• Example : SI unit for measurement of length is meter , SI unit for measurement of mass is kilogram, SI unit for measurement of time is second.

Among the given units :

• Lunar month is the unit of time
• Candela is the unit of luminous intensity
• Kelvin is the unit of temperature
• Light year is the unit of length.

So, light year is the only unit of length in this case. (1 light year means the distance travelled by light in 1 year)

Hence, the unit of length is light year.