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Nuclei — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsNuclei1 Mark
MCQ
For question, statements are given-one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $(a) (b) (c)$ and $(d)$ as given below. Assertion $(A$): The ratio for time taken for light emission from an atom to that for release of nuclear energy in fission is $1 : 100$.
Reason $(R)$: Time taken for the light emission from an atom is of the order of $10^{-8}s$.
  • ✓
    Both $A$ and $R$ are true, and $R$ is the correct explanation of $A$.
  • B
    Both $A$ and $R$ are true, but $R$ is $\text{NOT}$ the correct explanation of $A$.
  • C
    $A$ is true, but $R$ is false.
  • D
    $A$ is false and $R$ is also false.
✓

Answer

Correct option: A.
Both $A$ and $R$ are true, and $R$ is the correct explanation of $A$.
Time taken for the light emission from an atom $\approx10^{-8}\text{s}$
Time taken for release of energy in fission $\approx10^{-6}\text{s}$
Required ratio $=\frac{10^{-8}}{10^{-6}}=\frac{1}{100}=1 :100$

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