ANSWER: The ABUNDANCE in % for other two ISOTOPES of the oxygen is 99.762% and 0.201%

Explanation :

The average atomic mass of an ELEMENT is the total of isotopic mass times the percent abundance for all the isotopes.

Oxygen has 3 isotope, 160, '70 and 180.

The average atomic mass of oxygen can be calculated as follows.

Average Atomic Mass = (Isotopic mass of 160 x % abundance of 160) + (isotopic mass of "0 x % abundance of "O) + (Isotopic mass of 180 x % abundance of 180)

17 The mass of "O = 16.999 amu and its % abundance is 0.037% which is 0.00037

The mass of 160 = 15.995 amu. Let us assume its % abundance as a

The mass of 180 = 17.999 amu

The total % abundance for all the isotopes is 100% or 1.

Therefore % abundance for 180 would be 1- (a + 0.00037) = 0.99963 a =

Let us plug in the above values in the average atomic mass formula.

Average atomic mass = ( 15.995)(a) + = (16.999)(0.00037) + (17.999)(0.99963 - a)

The average atomic mass of element O is 15.9994

Therefore we have,

15.9994 = 15.995a + 0.0062896 + 17.99234 - 17.999a

15.9994 = -2.004a + 17.99863

-1.99923 = -2.004a

a = 0.99762

a = 99.762%

The percent abundance of 16 O is

99.762%

The percent abundance of 180 is 0.99963 - 0.99762 = 0.00201 or 0.201%

50.