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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
- Ohm’s law is not applicable except to
- Which of the following measurement is most precise?
- 300j work is done in sliding a 2kg block up an inclined plane of height 10m
- The drive shaft of an automobile rotates at 3600 rpm and transmits 80 HP
- An objective moves ,starting from rest through a resistive medium
Topics: Radioactivity (83)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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