Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET Medical202625 April 2026Morning ShiftPhysicsNuclear PhysicsActual

The activity of a freshly prepared radioactive sample of a radioisotope is 10¹⁰ disintegrations per second. The average life ( ) of this isotope is 10^9 s , and the mass of a single atom of this isotope is 10⁻²⁵ kg . The total mass of the radioactive sample is

Options

  1. A0.1 mg
  2. B1 mg
  3. C10 mg
  4. D100 mg

Correct answer

B. 1 mg

Step-by-step solution

The activity of a radioactive sample is given by A = N , where is the decay constant and N is the number of active nuclei. The average life is related to the decay constant by = 1 . Substituting = 1 into the activity equation, we get: A = N N = A Given A = 10¹⁰ s ⁻¹ and = 10^9 s , the number of atoms is: N = 10¹⁰ 10^9 = 10¹⁹ The total mass M of the radioactive sample is the product of the number of atoms and the mass of a single atom m : M = N m Given m = 10⁻²⁵ kg , we have: M = 10¹⁹ 10⁻²⁵ kg = 10⁻⁶ kg Converting t

Practice Nuclear Physics on Quantrex Academy →

More from Nuclear Physics

Consider the following nuclear fission reaction ₀^1 n + ₉₂²³⁵U _Z^A Y + ₄₁⁹⁹Nb + neutrons . If 4 neutrons are released during the fission process, then A and Z are 2026Two spherical nuclei have mass numbers 216 and 64 with their radii R₁ and R₂ respectively. The ratio R₁ R₂ is 2026At time t = 0 , the activity of a radioactive substance is 1600 Bq. At t= 8 s, the activity remains 100 Bq. The activity at t = 2 s, the is 2026A radioactive nucleus ₉₂X²³⁵ decays to ₉₁Y²³¹ . Which of the following particles are emitted? 2026In a given reaction, ^ A _ Z X ^ A _ Z+1 Y ^ A-4 _ Z-1 K ^ A-4 _ Z-1 K the radioactive radiations are emitted in the sequence of 2026When a nucleus in an atom undergoes a radioactive decay, the atomic number and/or mass number of the atom 2026A common example of ^- decay is ₁₅ P ³² ₁₆ S ³² + x + y Then x and y , respectively, stand for 2026For a radioactive nucleus that undergoes ^+ decay, which of the following CANNOT occur? 2026 Full Nuclear Physics list All MHT CET Medical PYQs