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Nuclei — Physics STD 12 Science — Question

Gujarat 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 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 $\approx10^{-6}\text{s}$
$\text{Required ratio}=\frac{10^{-8}}{10^{-6}}=\frac{1}{100}=1 :100$

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