Activity of Radioactive Elements Numerical Class-12 Nootan ISC Physics Solution Ch-28 Radioactivity. Step by step solutions of Kumar and Mittal Physics of Nageen Prakashan as council latest prescribe guideline for upcoming exam. Visit official Website CISCE for detail information about ISC Board Class-12 Physics.
Activity of Radioactive Elements Numerical Class-12 Nootan ISC Physics Solution Ch-28 Radioactivity
| Board | ISC |
| Class | 12 |
| Subject | Physics |
| Book | Nootan |
| Chapter-28 | Radioactivity |
| Topics | Numericals on Activity of Radioactive Elements |
| Academic Session | 2025-2026 |
Numericals on Activity of Radioactive Elements
Class-12 Nootan ISC Physics Solution Ch-28 Radioactivity
Que-21: Compute the activity of one gram of Th232 whose decay constant is 1.58 x 10^-18 s^-1. Take Avogadro’s number 6.02 x 10^23/mole.
Ans- We know that
R = -dN/dt = λN
Que-22: The half-life of a radioactive material is 40 days. What time will it take for the activity to drop to 30% of its initial value? loge 2 = 0.6931 and loge (10/3) = 1.20.
Ans- We know that R/Ro = N/No = 30%
=> 30/100 = 0.3
∴ T = 48/0.6931 = 69.2 Days
Que-23: 2.0 x 10^-5 gram of Au200 has a decay rate (activity) of 60 curie. Compute its half-life. Take Avogadro’s number 6.02 x 10^23/mole.
Ans- Given R = 60 curie = 60 x 3.7 x 10^10 sec^-1
N = 6.02 x 10^23 x 2 x 10^-5 / 100 = 6.02 x 10^16
We know that
Que-24: 1 gram of Cs137 decays with a half-life of 30 years. If the initial activity of Cs137 is 1.0 mc (millicurie), find (i) number of atoms left after 5 years, (ii) the activity after 5 years. The Avogadro’s number is 6.02 x 10^23 per mole. Take (0.5)^1/6 = 0.89.
Ans- Na = 1 gm , T1/2 = 30 year
t = 5 years
R = 1.0 mc = 1.0 x 10^3 x 3.7 x 10^10 = 3.7 x 10^7
Que-25: Calculate the mass of Co60 required to provide a radioactive source of 8.0 curie strength. The half-life of Co60 is 5.3 years. Take Avogadro’s number 6.02 x 10^23 mole^-1.
Ans-
The mass of Co60
=> 71..88 x 10^-6
=> 7.1088 x 10^-5
=> 7.1 mg
–: Activity of Radioactive Elements Numerical Class-12 Nootan ISC Physics Solution Ch-28:–
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