The correct option is B 6:3:2
Bohr's radius for nth orbit, rn=0.529[n2Z]∘A
where n=Energy level, Z=Atomic number
For H atom: n=1, Z=1
rH=0.529[121]∘A
For He+ ion: n=1, Z=2
rHe+=0.529[122]∘A
For Li2+ ion: n=1, Z=3
rLi2+=0.529[123]∘A
Upon taking ratio, rH:rHe+:rLi2+=1:12:13
On simplifying, we get the ratio as:
6:62:63 i.e., 6:3:2