Home
Class 12
PHYSICS
A radioactive element has half-life peri...

A radioactive element has half-life period of 30 days. How much of it will be left after 90 days?

A

`13.5%`

B

`46.5%`

C

`87.5%`

D

`90.15%`

Text Solution

Verified by Experts

The correct Answer is:
C
`90 "days" rarr 3 "half lives"`, left `1/8` i.e., `12.5%`
Disintegrated `= 100-12.5 = 87.5%`
Promotional Banner

Topper's Solved these Questions

  • SIMPLE HARMONIC MOTION

    ALLEN |Exercise Exercise-02|19 Videos

  • SIMPLE HARMONIC MOTION

    ALLEN |Exercise Exercise- 3 Match The Column|1 Videos

  • SIMPLE HARMONIC MOTION

    ALLEN |Exercise SOME WORKED OUT EXAMPLES|29 Videos

  • RACE

    ALLEN |Exercise Basic Maths (Wave Motion & Dopplers Effect) (Stationary waves & doppler effect, beats)|25 Videos

  • TEST PAPER

    ALLEN |Exercise PHYSICS|4 Videos

Similar Questions

Explore conceptually related problems

A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to a) 3.125%, b) 1% of its original value?

Half-life period of a radioactive element is 100 seconds. Calculate the disintegration constant and average life period. How much time will it take for 90% decay?

A radioactive sample has a half life of 40 seconds. When its activity is measured 80 seconds after the beginning, it is found to be 6.932xx10^(18) dps. During this time total energy released is 6xx10^(8) joule (ln2=0.6932) :-

1 gram of a radioactive element reduces to 1/3 gram at the end of 2 days. Then the mass of the element remaining at the end of 6 days is- [gram]

The half - line period a radioactive element X is same as the mean life time of another radioactive element Y . Initially both of them have the same number of atoms. Then:

Half-life for certain radioactive element is 5 min . Four nuclei of that element are observed at a certain instant of time. After 5 minutes STATEMENT-I: It can be definitely said that two nuclei will be left undecayed. STATEMENT-II: After half-life that is 5 minutes, half of totan nuclei will disintegrate. So, only two nuclei will be left undecayed.

If N_(0) is the original mass of the substance of half - life period t_(1//2) = 5 year then the amount of substance left after 15 year is

As accident in a nuclear laboratory resulting in deposition of a certain amount of radioactive material of half life 18 days inside the laboratory Tests revealed that the radiation was 64 times more than the permissible level required for save operation of the laboratory what is the minimum number of days after which the laboratory can be considered safe for use?

ALLEN -SIMPLE HARMONIC MOTION-Exercise-01
  1. The constant 'a' Mosely's law sqrt(v) - a(Z-b) for k(alpha)X-rays is r...

    Text Solution

    |

  2. Characteristic X-rays are not obtained in the spectrum of H-atom becau...

    Text Solution

    |

  3. For the decay of nucleus, the possible reason which is not true

    Text Solution

    |

  4. Assuming that 200MeV of energy is released per fission of uranium ato,...

    Text Solution

    |

  5. If the binding energy per nucleon in .(3)Li^(7) and .(2)He^(4) nuclei ...

    Text Solution

    |

  6. The mass of proton is 1.0073 u and that of neutron is 1.0087 u (u= ato...

    Text Solution

    |

  7. The binding energy of deuteron is 2.2 MeV and that of .(2)^(4)He is 28...

    Text Solution

    |

  8. In an alpha -decay, the kinetic energy of alpha-particles is 48 MeV a...

    Text Solution

    |

  9. When a neutron is disintegrated, it gas :-

    Text Solution

    |

  10. If N(t) = N(o)e^(lambdat) then number of disintefrated atoms between t...

    Text Solution

    |

  11. A radioactive element has half-life period of 30 days. How much of it ...

    Text Solution

    |

  12. The half life of a radioactive element is 10 days, if the mass of the ...

    Text Solution

    |

  13. In a mean life of a radioactive sample

    Text Solution

    |

  14. Atomic weight of a radioactive element is M(W) gm. Radioactivity of m ...

    Text Solution

    |

  15. Radioactive element decays to form a stable nuclide, then the rate of ...

    Text Solution

    |

  16. The probability of nucleus to decay in two mean lives is

    Text Solution

    |

  17. A sample of radioactive material decays simultaneouly by two processes...

    Text Solution

    |

  18. Find the Q - value for the nuclear reaction: .(2)He^(4)+.(7)N^(14) r...

    Text Solution

    |

  19. Starting with a sample of pure .^66 Cu, 7//8 of it decays into Zn in 1...

    Text Solution

    |

  20. Consider the following energies :- 1. minimum energy needed to excit...

    Text Solution

    |