Question

Chlorine exists in two isotopic forms `Cl-37` and Cl-35 but its atomic mass is 35.5. this indicates the ratio of Cl-37 and Cl-35 is appromimately
A. `1 : 2`
B. `1 : 1`
C. `1 : 3`
D. `3 : 1`

Answer 1

Correct Answer - C
Let the % of Cl-37 isotope=x
`:. ` the % of Cl-35 isotope=(35-x)
`(37xx x )/(100) + (35xx(100-x))/(100)=35.5`
`37x-35x=3550-3500`
`2x=50 or x=25`
`:.` the two isotopes are in the ratio `25 : 75` or `1:3`.