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JEE Main 20211 SeptemberEvening Shift
Exam
JEE Main
Year
2021
Date
1 September
Shift
Evening Shift
Subject
Physics
Chapter
Nuclear Physics

JEE Main 2021 · 1 September · Evening Shift · Physics · Nuclear Physics

The half life period of a radioactive element x is same as the mean...

The half life period of a radioactive element xx is same as the mean life time of another radioactive element y.y . Initially they have the same number of atoms. Then:

Options

  1. Axx and yy decay at the same rate always.
  2. Bxx-will decay faster than y.y .
  3. Cyy-will decay faster than x.x .
  4. Dxx and yy have same decay rate initially and later on different decay rate.

Correct answer

C. yy-will decay faster than x.x .

Step-by-step solution

The formula of half-life in terms of the decay constant, t12=0.693λx=1λyt\dfrac{1}{2} = \dfrac{0 . 693}{{\lambda}_{x}} = \dfrac{1}{{\lambda}_{y}}
⇒λx=0.693λy⇒λx<λy⇒ {\lambda}_{x} = 0 . 693{\lambda}_{y} ⇒ {\lambda}_{x} < {\lambda}_{y}
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