Question

Which of the following is emitted when $^{239}_{94} Pu$ decays into $^{235}_{92}U$ ?

• A. Gamma Ray
• B. Neutron
• C. Electron
• D. Alpha particle

Answer 1

Answer: (D)

Alpha particle

Answer 2

The correct answer is D:Alpha particle
From the above question the reaction taking place is;
$_{94}Pa^{239}\rightarrow^A_ZX+ _{92}U^{235}$
Conservation of atomic number and mass number would be;
$239=A+235\implies A=4$
$94=Z+92\implies Z=2$
From above solution we can conclude that the particle emitted is $^4_2He$ that is termed to be an alpha particle.