Question

Naturally occurring chlorine consists of two isotopes whose atomic masses are 35 and 37. The average atomic weight of natural chlorine is 35.5. If the ratio of cl35 and cl37 is
a.B the numerical value of a/b will be

Answer 1

Explanation:

The percent abundance of Cl-35Cl−35 and Cl-37Cl−37 is equal to 100.

Let abundance of ^{35}Cl = x

35

Cl=x and abundance of ^{37}Cl = 100-x

37

Cl=100−x.

As we know,

Atomic weight of ^{35}Cl =

35

Cl= 34.9689

Atomic weight of ^{37}Cl =

37

Cl= 36.9695

Atomic mass of Cl =Cl= 35.45

Average atomic mass = \dfrac{34.9689(x)+36.9695(100-x)}{100} =35.45

100

34.9689(x)+36.9695(100−x)

=35.45

x= 76\%x=76%

Abundance of Cl-35Cl−35 = 76%

Abundance of Cl-37Cl−37 = 24%

Hence, the ratio of their natural abundance is approximately equal to 3:13:1.