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At a given time, 25% of the nuclei prese...

At a given time, 25% of the nuclei present in a sample is radioactive. After 10 s that amount reduces to 12.5%. After what time from the beginning, 0.78% of the nuclei present in the sample would be radioactive?

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The initial number of radioactive atoms in a radioactive sample is N_0 . If after time t the number of becomes N, then N=N_0e^(-lambdat) , where lambda is known as the decay constant of the element. The time in which the number of radioactive atoms becomes half of its initial number is called the half-life (T) of the element. The time in which the number of atoms falls to 1/e times of its initial number is the mean life (tau) of the element. The product lambdaN is the activity (A) of the radioactive sample when the number of atoms is N. The SI unit of activity is bequerel (Bq)' where 1 Bq = 1 decay. s^(-1) . The half-life of Iodine-131 is 8 d. Its mean life (in SI) is - (A) 4.79xx10^5 s. (B) 6.912xx10^5 s. (C) 9.974 xx 10^5 s. (D) 22.96xx10^5 s.

The initial number of radioactive atoms in a radioactive sample is N_0 . If after time t the number of becomes N, then N=N_0e^(-lambdat) , where lambda is known as the decay constant of the element. The time in which the number of radioactive atoms becomes half of its initial number is called the half-life (T) of the element. The time in which the number of atoms falls to 1/e times of its initial number is the mean life (tau) of the element. The product lambdaN is the activity (A) of the radioactive sample when the number of atoms is N. The SI unit of activity is bequerel (Bq)' where 1 Bq = 1 decay. s^(-1) . The half-life of Iodine-131 is 8 d. What is the activity (in Bq) of 1 g of Iodine? (A) 2.3xx10^15 (B) 4.6xx10^15 (C) 6.9xx10^15 (D) 9.2xx10^15

The initial number of radioactive atoms in a radioactive sample is N_0 . If after time t the number of becomes N, then N=N_0e^(-lambdat) , where lambda is known as the decay constant of the element. The time in which the number of radioactive atoms becomes half of its initial number is called the half-life (T) of the element. The time in which the number of atoms falls to 1/e times of its initial number is the mean life (tau) of the element. The product lambdaN is the activity (A) of the radioactive sample when the number of atoms is N. The SI unit of activity is bequerel (Bq)' where 1 Bq = 1 decay. s^(-1) , and Avogadro's number, N=6.023xx10^23 What is the ratio of activity of same amount of sodium-24 to that of iodine-131? [half life of sodium-24 is 15h.] (A) 1/70 (B) 1/7 (C) 7 (D) 70

The initial number of radioactive atoms in a radioactive sample is N_0 . If after time t the number of becomes N, then N=N_0e^(-lambdat) , where lambda is known as the decay constant of the element. The time in which the number of radioactive atoms becomes half of its initial number is called the half-life (T) of the element. The time in which the number of atoms falls to 1/e times of its initial number is the mean life (tau) of the element. The product lambdaN is the activity (A) of the radioactive sample when the number of atoms is N. The SI unit of activity is bequerel (Bq)' where 1 Bq = 1 decay. s^(-1) , The half-life of Iodine-131 is 8d. Its decay constant (in SI) is - (A) 10^(-6) (B) 1.45xx10^(-6) (C) 2xx10^(-6) (D) 2.9xx10^(-6)

The half-life of a radioactive element is 3 min. If the initial mass of the element be 1 g then after what time 0.0625 g of the element remains intact?

CHHAYA PUBLICATION-ATOMIC NUCLEUS-EXERCISE
  1. A radioactive nucleus X decays as follows : A overset(beta^+)to A1 ove...

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  2. The mass of a proton is 1.00816 u and that of a neutron is 1.00902 u. ...

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  3. At a given time, 25% of the nuclei present in a sample is radioactive....

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  4. The masses of a proton and a neutron are 1.0073 u and 1.0087 u , respe...

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  5. If 1 u = 1.66xx10^(-27) kg and average radius of a nucleus is 1.2xx10^...

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  6. The rate of disintegration of a radioactive element at any instant is ...

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  7. The half-life of a radioactive element is 8 d . If the initial mass of...

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  8. The half-life of a radioactive element is 1600 y. What part of the ele...

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  9. The half-life of a radioactive element is 3 min. If the initial mass o...

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  10. Initial mass of a radioactive element is 1 g. If 0.25 g of the element...

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  11. The half-life of a radioactive element is 1600 y. After what time 10% ...

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  12. One-fourth part of a radioactive element is disintegrated in 664 y. De...

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  13. The half-life of U^238 is 4.5xx10^9 y. In any radioactive sample if 1...

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  14. The activity of 1 g. of a sample of Po^210 is 4442 Ci. Determine the h...

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  15. The half-life of an isotope of carbon is 6000 y. In how many years the...

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  16. The half-life of a radioactive element is 2h. If its initial mass be 5...

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  17. The half-life of Radon is 3.8 d. After how many days 1/20 part of some...

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  18. If a radioactive substance disintegrates by 20% in 5d, then what part ...

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  19. Radioactive isotope Th^232 (Z = 90) emits six alpha-particles and four...

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  20. The half-life of a radio-isotope is 3 min. What fraction of the number...

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