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Question: Answered & Verified by Expert
${ }_{92}^{238} \mathrm{U}$ has 92 protons and 238 nucleons. It decays by emitting an alpha particle and becomes
PhysicsNuclear PhysicsAIIMSAIIMS 2006
Options:
  • A ${ }_{92}^{234} \mathrm{U}$
  • B ${ }_{90}^{234} \mathrm{Th}$
  • C $235 \mathrm{U}$
  • D ${ }_{93}^{237} \mathrm{~Np}$.
Solution:
1394 Upvotes Verified Answer
The correct answer is: ${ }_{90}^{234} \mathrm{Th}$
Emission of alpha particle, decrease the mass number by 4 and charge number by 2 .
$\therefore$ Decrease in mass number $=238-4=234$
Decrease in charge number $=92-2=90$ ${ }_{90}^{234} \mathrm{Th}$ is emitted.

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