The atomic mass of chlorine is listed as 35.454 amu on the periodic table. It has two naturally occurring isotopes, Cl-35 and Cl-37. What are the approximate percentages of each?

X=percentage of Cl-35

(1-x) = percentage of Cl-35

35 (x) + 37 (1-x) = 35.454

35x+37-37x=35.454

-2x=35.454-37

-2x=-1.546

x=-1.546 / (-2)

x=0.773

0.773=77.3/100=77.3%

(1-x) = 1-0.773=0.227

0.227=22.7/100=22.7%

answer: the percentages are: 77.3% of Cl-35 and 22.7% of Cl-37.