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The half life of radium is about 1600 year. Of 100 gram of radium existing now, 25g will remain unchanged after
Options
(a) 4800 year
(b) 6400 year
(c) 2400 year
(d) 3200 year
Correct Answer:
3200 year
Explanation:
100 gram at beginning, I = 0
25 gram remains undecayed.
N / N₀ = (1 / 2)ⁿ ⇒ 25 / 100 = (1 / 2)ⁿ
⇒ 1 / 4 = (1 / 2)ⁿ
Therefore, n = 2
Time = n × T
= 2 × 1600
= 3200 years.
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Topics: Radioactivity
(83)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- When the angle of incidence is 60° on the surface of a glass slab, it is found
- The ionisation potential of hydrogen-atom is -13.6 eV. An electron in the groundstate
- A block of mass 0.50 kg is moving with a speed of 2.00 ms⁻¹ on a smooth surface.
- A solid cylinder of mass 50kg and radius 0.5 m is, free to rotate about the horizontal axis
- If the length of a stretched string is shortened by 4% and the tension is increased
Topics: Radioactivity (83)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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