Physics Nuclear Physics UHS 2024
PMDC Verified Question 6 of 98
The unit of decay constant is:
A
m
B
s
C
\(\text{s}^{-1}\)
D
\(\text{m}^{-1}\)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: \(\text{s}^{-1}\)


Concept:

Determine the units of the decay constant (\(\lambda\)) through its foundational mathematical formula.

Formula:

$$ \lambda = \frac{0.693}{T_{1/2}} $$

Solution:

  • The numerator (0.693) is a dimensionless numerical constant.


  • The denominator (\(T_{1/2}\)) is half-life, which is measured in time units, fundamentally seconds (\(s\)).


  • Therefore, dividing a dimensionless number by seconds yields a unit of \( \frac{1}{s} \) or \(\text{s}^{-1}\).


  • Note: It represents the fractional probability of decay per second.


Why other options are incorrect:

Option B (s) is the unit of time (half-life), not the constant. Options A and D represent length.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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