He:li

We will use the formula [r=k/z] And here k=1

He= 1/2 : Li= 1/3 your ratio is 2:3

I might not be able to explain my answer but answer is correct

Answer:

The correct option is 3.

Explanation:

= radius of the nth shell

Z = Atomic number

Radius of first orbit of

n=1, Z = 2

..(1)

Radius of second orbit of

n=2, Z = 3

..(2)

Dividing (1) to (2):

Hence, the correct option is 3.