question_answer

An element X decays, first by positron emission and then two \[\alpha \]-particles are emitted in successive radioactive decay. If the product nuclei has a mass number 229 and atomic number 89, the mass number and atomic number of element X are -

A) 237, 93

B) 237, 94

C) 221, 84

D) 237, 92

Correct Answer: B

Solution :

Given \[A-8=224.\] \[Z-5=89\]                     \[\Rightarrow A=237,Z=94.\]