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The half life of radioactive isotope ‘X’ is 50 years. It decays to another element ‘Y’ which is stable. The two elements ‘X’ and ‘Y’ were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be
Options
(a) 150 years
(b) 200 years
(c) 250 years
(d) 100 years
Correct Answer:
200 years
Explanation:
Let no. of atoms in X = Nₛ, No. of atoms in Y = Nₜ
By eq. Nₛ / Nₜ = 1/15
Part of Nₛ = 1/16 (Nₛ + Nₜ) = 1/2⁴ (Nₛ + Nₜ)
So, total 4 half lives are passed, so, age of rock is 4 x 50 = 200 years.
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Topics: Radioactivity
(83)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A scooter is going round a circular road of radius 100 m at a speed of 10m/s
- Three particles A,B and C are thrown from the top of a tower with the same speed.
- A person can see clearly objects only when they lie between 50 cm and 400 cm from
- Huygen’s wave theory allows us to know
- The wavelength of the short radio waves, microwaves, ultraviolet waves are λ₁,λ₂ and λ₃
Topics: Radioactivity (83)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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