1) 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: Option DExplanation: $^{239}_{94}Pu$ $\underrightarrow{a}$ $^{235}_{92}U$ When $\alpha$- particle is emitted that atomic mass is decreases by four and atomic number is decreases by two
