Which parent nucleus would emit an -particle to form ?

PHYSICS · Single correct · CBSE · Physics · Nuclei · Nuclei

Problem

Which parent nucleus would emit an

\alpha

-particle to form

^{238}_{90}\text{Th}

? (a)

^{238}_{92}\text{U}

(b)

^{242}_{92}\text{U}

(c)

^{234}_{88}\text{Ra}

(d)

^{242}_{91}\text{Pa}