PhysicsNEET 2023Radioactivity and decay law

Nuclei

The half-life of a radioactive substance is 20 minutes. In how much time does the activity of the substance drop to $\frac{1}{16}$ th of its initial value?

A.20 minutes
B.40 minutes
C.60 minutes
D.80 minutes✓

You have the answer. The worked solution — and why the other three were written — is part of a paid pack.

More from this chapter in past papers

^{290} {82}X {\ \ } Y {\ e^{+}\ } Z {\ e^{-}\ } P {\ e^{-}\ } Q In the nuclear emission…NEET 2024
In the given nuclear reaction, the element X is: ^{22} {11} {Na} {X} + e^{+} +NEET 2022
A radioactive nucleus ^{A} {Z} {X} undergoes spontaneous decay in the sequence ^{A} {Z}…NEET 2021
The half-life of a radioactive nuclide is 100 hours. The fraction of the original…NEET 2021
An -particle consists of:NEET 2019

From Physics › Nuclei › Radioactivity and decay law — lectures, notes and every past question on it.

Last revised 7 Sept 2026. Found a mistake? Tell us — corrections are the fastest thing we act on.

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