The ratio of radii of nuclei `._13 A1^27` and `._52 X^A` is `3 : 5`. The number of neutrons in the nuclei of `X` will be

Options

A. 52
B. 73
C. 125
D. 13

Answer

B

Explanation

(b) `r prop A^(1//3) rArr (r_1)/(r_2) = ((A_1)/(A_2))^(1//3)`
`rArr (3)/(5)=((27)/(A))^(1//3) rArr (27)/(125) - (24)/(A) rArr A = 125`
Number of nuclei in atom `X = A - 52`
=`125 - 52 = 73`.