Question

Chlorine consists of a mixture of two isotopes of masses 35 and 37 in the ratio of ______.

Options

• 1 : 3

• 3 : 1

Answer 1

Chlorine consists of a mixture of two isotopes of masses 35 and 37 in the ratio of 3 : 1.

Explanation:

Naturally occurring chlorine has an average atomic mass of approximately 35.5 u. This fractional value exists because chlorine is a mixture of the isotopes Chlorine-35 and Chlorine-37, which occur in a 3 : 1 abundance ratio (roughly 75% and 25%, respectively). Mathematically, calculating the weighted average based on this 3 : 1 ratio yields the exact fractional mass:

`((35 xx 3) + (37 xx 1))/4` = 35.5 u