Student Login

Home›Chapters›Nuclear Physics PYQs›Law of Radioactive Decay›Question 73

JEE Main 2020 (5 Sep, Shift 2) · Law of Radioactive Decay

Law of Radioactive Decay question from JEE Main 2020 (5 Sep, Shift 2)

Q73JEE Main 2020 · 5 SEP · SHIFT 2Easy

Law of Radioactive Decay

A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the second is 100 s. The effective half life of the nucleus is close to:

Show answer and solution

Answer: (b)

Parallel decay: $\frac{1}{T} = \frac{1}{T_1} + \frac{1}{T_2}$ .
$T = \frac{10\times100}{10+100} = \frac{1000}{110} \approx 9.1$ s.
So the answer is (b) 9 sec.

Report a mistake

More questions on Law of Radioactive Decay

In a radioactive material, fraction of active material remaining after time t is 9/16…JEE Main 2020 (3 Sep, Shift 1)
The half life of a radioactive sample undergoing α -decay is 1.4 × 10¹⁷ s. If the number…NEET 2020 (Phase 2)
The activity of a radioactive sample falls from 700 s–1 to 500 s–1 in 30 minutes. Its…JEE Main 2020 (7 Jan, Shift 2)
Activities of three radioactive substances A, B and C are represented by the curves A, B…JEE Main 2020 (5 Sep, Shift 1)
The rate of radioactive disintegration at an instant for a radioactive sample of half…NEET 2019
Using a nuclear counter the count rate of emitted particles from a radioactive source is…JEE Main 2019 (10 Jan, Shift 1)
Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively…JEE Main 2019 (12 Apr, Shift 2)
Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t = 0…JEE Main 2019 (10 Apr, Shift 2)