Answer:
The abundance of 35/17 Cl is 75% and 25% of 37/17Cl
Explanation:
The molar mass of an atom is defined as the sum of the masses of each isotope times its abundance, that is:
35.5amu = 35amu*X + 37amu*Y (1)
Where X is the abundance of the 35/17Cl and Y the abundance of 37/17 Cl
As there are just these 2 isotopes and the abundances of both isotopes = 1:
X + Y = 1 (2)
Replacing (2) in (1):
35.5 = 35X + 37(1-X)
35.5 = 35X + 37 - 37X
-1.5 = -2X
X = 0.75 = 75%
And Y = 100-75% = 25%
The abundance of 35/17 Cl is 75% and 25% of 37/17Cl
