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Q53 (NDA-II/2025) NA › NA

One parsec in astronomical units (A.U.) is about

Result
Your answer:  ·  Correct: C

Explanation

A parsec (pc) is an astronomical unit of length used to measure large distances to objects outside our Solar System. It is defined as the distance at which one Astronomical Unit (AU) subtends an angle of one arcsecond.

To find the value in AU, we use the relationship:

  • 1 parsec = 1 AU / tan(1")
  • For very small angles, tan(θ) ≈ θ (in radians).
  • 1 arcsecond = 1 / (60 × 60 × 180 / π) radians ≈ 4.848 × 10⁻⁶ radians.
  • 1 parsec ≈ 1 / (4.848 × 10⁻⁶) AU ≈ 206,265 AU.

In scientific notation, this is approximately 2.06 × 10⁵ AU, which makes option C the correct choice.

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