Radioactivity & Radioactive Decay Law questions with solutions

Showing 1–10 of 127 questions

• Multi-correctmediumNuclear physicsRadioactivity & Radioactive Decay Law

  A radioactive nucleus has decay constant λ. Which statements are correct?

  Select all that apply

  • Option A

    The probability of survival up to time t is exp(-λt)

  • Option B

    The probability of decay before time t is 1-exp(-λt)

  • Option C

    If the nucleus has survived up to some instant, the probability that it decays during a very small following interval dt is approximately λdt

  • Option D

    The probability per unit time of decay increases continuously as the nucleus becomes older

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• NumericeasyNuclear physicsRadioactivity & Radioactive Decay Law

  A radioactive substance has half-life 5 years. The probability of decay in 10 years, in percent, is 3n. Find n.

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• NumericmediumNuclear physicsRadioactivity & Radioactive Decay Law

  A source contains two independent radioactive isotopes X and Y. Initially each isotope contributes an activity of 1600 Bq. The half-life of X is 2 h and the half-life of Y is 4 h. If the total activity after 4 h is N Bq, find N.

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• MCQmediumNuclear physicsRadioactivity & Radioactive Decay Law

  Which of the following represents the correct β⁻ decay of a neutron?

  Options

  • Option A

    n → p + e⁻ + ν

  • Option B

    n → p + e⁺ + ν̄

  • Option C

    n → p + e⁺ + ν

  • Option D

    n → p + e⁻ + ν̄

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  JEE Mains 2025 28 Jan Morning Shift

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• NumericmediumNuclear physicsRadioactivity & Radioactive Decay Law

  A modern carbon sample gives 85 counts per minute in a detector, whereas an ancient wooden sample of identical carbon content gives 25 counts per minute. The detector background is 5 counts per minute in both cases. If the half-life of carbon-14 is 5730 years, find the age of the wooden sample in years.

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• MCQeasyNuclear physicsRadioactivity & Radioactive Decay Law

  A neutron-rich nucleus ᴬZX undergoes β⁻-decay. The parent nucleus is initially at rest. Which reaction correctly shows the change of the nucleus and the leptons required for conservation of charge, energy and lepton number?

  Options

  • Option A

    ᴬZX → ᴬ(Z+1)Y + e⁻ + ν̄ₑ

  • Option B

    ᴬZX → (A-1)(Z+1)Y + e⁻

  • Option C

    ᴬZX → ᴬ(Z-1)Y + e⁺ + νₑ

  • Option D

    ᴬZX + e⁻ → ᴬ(Z+1)Y

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• MCQmediumNuclear physicsRadioactivity & Radioactive Decay Law

  A radioactive sample S₁ has activity 5 μCi and contains twice as many nuclei as another sample S₂, whose activity is 10 μCi. Which pair can be the half-lives of S₁ and S₂?

  Options

  • Option A

    20 years and 5 years, respectively

  • Option B

    20 years and 10 years, respectively

  • Option C

    10 years each

  • Option D

    5 years each

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• MCQeasyNuclear physicsRadioactivity & Radioactive Decay Law

  A nucleus at rest disintegrates into two smaller nuclei with their masses in the ratio of 2:1. After disintegration they will move :-

  Options

  • Option A

    In opposite directions with speed in the ratio of 1:2 respectively

  • Option B

    In opposite directions with speed in the ratio of 2:1 respectively

  • Option C

    In the same direction with same speed.

  • Option D

    In opposite directions with the same speed.

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  JEE Mains 2024 09 Apr Evening Shift

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• MCQmediumNuclear physicsRadioactivity & Radioactive Decay Law

  A neutral parent atom has mass 210.0200 u. After α-decay, the neutral daughter atom and helium atom have masses 206.0120 u and 4.0026 u respectively. Take 1 u·c² = 931.5 MeV. The Q-value is closest to:

  Options

  • Option A

    2.5 MeV

  • Option B

    5.0 MeV

  • Option C

    7.5 MeV

  • Option D

    10 MeV

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• NumericmediumNuclear physicsRadioactivity & Radioactive Decay Law

  Two radioactive sources S₁ and S₂ have equal activity at t=0, activity is defined as $A=-\frac{dN}{dt}$. Later, S₁ and S₂ have just completed 3 and 7 half-lives, respectively. Find A₁/A₂.

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