When ²³⁸U emits an $\alpha$ -particle and two $\gamma$ -rays, A) ²³⁴U is produced. B) ²³⁸Th is produced. C) ²³⁴Th is produced. D) ²³⁶Th is produced. E) ²⁴²Pu is produced.

Question

Quizplus · Accepted Answer

When an atom emits an $\alpha$-particle, its atomic number decreases by 2 and its mass number decreases by 4. The emission of $\gamma$-rays does not change the atomic or mass numbers. Therefore, starting from ²³⁸U (which seems to represent uranium-238), after emitting an $\alpha$-particle, the element becomes thorium (Th) with atomic number 90 (92-2) and mass number 234 (238-4), which matches option C.

When 238U Emits An α\alphaα -Particle and Two γ\gammaγ -Rays, A) 234U Is Produced

When ²³⁸U Emits An $\alpha$ -Particle and Two $\gamma$ -Rays,
A) ²³⁴U Is Produced