Which of the Following is/are not a unit of Time?

Answer: Both (1) and (3)

Explanation:

Parsec (parallactic second):

• It’s the distance that light travels in a vacuum in a year
• A light-year is used in astronomy to measure the distances of nearby stars and subtends an angle of 1 second of arc
• 1 parsec = 3.08 × 1016 m

Light year:

• It’s the distance that light travels in a vacuum in a year
• A light-year is used in astronomy to measure the distances of nearby stars

1 light-year = 1 ly = 9.467 × 1015 m .

• A parsec is a unit of length used to measure the great distances between celestial objects outside of our solar system
• Second: It is the (SI) unit of time
• Year: It is also a time unit

1 year = 365 days

1 day = 48 hours

1 hours = 3600 seconds

It is evident from the preceding discussion that a parsec and a light year are not time units. Hence, option (1) and (3) are correct.