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

Options

A. `237,93`
B. `237,94`
C. `221,84`
D. `237,92`

Answer

b

Explanation

`._X^AXoverset("Proton")(rarr)._(Z-1)^AYoverset(2alpha)rarr._(A-5)^(A-8)Y`
Given: `A-8 =224` and ` Z-5 =89`
`rArr A=237,Z=94`.