Physics Nuclear Physics UHS 2022
PMDC Verified Question 29 of 98
It has been observed that Thorium (\(_{90}^{234}\text{Th}\)) is transformed into Protactinium (\(_{91}^{234}\text{Pa}\)) after the emission of ____ particle:
A
Alpha
B
Beta
C
Gamma
D
Alpha, Beta, Gamma
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Beta


Concept:

Identify the emitted particle by applying the conservation of mass number (\(A\)) and atomic number (\(Z\)).

Solution:

  • Parent nucleus: \(_{90}^{234}\text{Th}\).


  • Daughter nucleus: \(_{91}^{234}\text{Pa}\).


  • Change in Mass Number (\(A\)): \(234 - 234 = 0\).


  • Change in Atomic Number (\(Z\)): \(91 - 90 = +1\).


  • A particle with mass number 0 and charge number -1 is an electron (\(_{-1}^{0}\text{e}\)), which corresponds to a Beta particle.


Why other options are incorrect:

Alpha emission would decrease mass by 4. Gamma emission would not change either number.

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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