Chlorine exists in two isotopic forms, Cl-37 and Cl-35 but its atomic mass is 35.5. This indicates t

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 approximately\

Professor PC Thomas Classes · Answer

(c): Let relative abundance of $\mathrm{Cl}-37=x \%$\ then relative abundance of $\mathrm{Cl}-35=(100-x) \%$\ Average atomic mass $=\frac{x 	imes 37+(100-x) 35}{100}=35.5$\ $\Rightarrow 37 x+3500-35 x=3550 \Rightarrow x=25 	herefore 100-x=75$\ Thus, the ratio of $\mathrm{Cl}-37$ and $\mathrm{Cl}-35$ is $x:(100-x)=25: 75=1: 3$\