Student Login

Home›Chapters›Nuclear Physics PYQs›Law of Radioactive Decay›Question 15

MHT CET 2025 (26 Apr, Shift 2) · Law of Radioactive Decay

Law of Radioactive Decay question from MHT CET 2025 (26 Apr, Shift 2)

Q15MHT CET 2025 · 26 APR · SHIFT 2Easy

Law of Radioactive Decay

A radio active element has rate of disintegration 8000 disintegrations per minute at a particular instant. After four minutes it becomes 2000 disintegrations per minute. The decay constant per minute is

Show answer and solution

Answer: (c)

$\frac{R}{R_0} = \frac{2000}{8000} = \frac{1}{4}$ , so 2 half-lives in 4 min.
$T_{1/2} = 2\text{ min}$ .
$\lambda = \frac{\ln 2}{2} = 0.5 \log_e 2\ \text{min}^{-1}$ .
So the answer is (c) $0.5 \log_e 2$ .

Report a mistake

More questions on Law of Radioactive Decay

A radioactive element has rate of disintegration 9000 disintegration per minute at a…MHT CET 2025 (25 Apr, Shift 1)
The activity of radioactive sample is measured as N₀ counts per minute at time t = 0, and…MHT CET 2025 (23 Apr, Shift 1)
Two radioactive materials A and B having decay constant ' 7λ ' and ' λ ' respectively…MHT CET 2025 (21 Apr, Shift 1)
A radioactive nucleus n₂ has 3 times the decay constant as compared to the decay constant…JEE Main 2025 (23 Jan, Shift 1)
A radioactive material P first decays into Q and then Q decays to non-radioactive…JEE Main 2025 (4 Apr, Shift 2)
A radioactive substance has half-life of 60 minutes. During 3 hours, the amount of…MHT CET 2024 (15 May, Shift 1)
Two radioactive substances A and B have decay constants ' 5λ ' and ' λ ' respectively. At…MHT CET 2024 (16 May, Shift 2)
Half-lives of two radioactive elements A and B are 30 minute and 60 minute respectively…MHT CET 2024 (4 May, Shift 2)