Suppose that a new element (E) were discovered that existed as three natural isotopes 25% of the atoms had - Science - Structure of the Atom

Question

Suppose that a new element (E) were discovered that existed as
three natural isotopes 25% of the atoms had a mass of 278, 38% had
a mass of 281, and the remainder had a mass of 285 What would be
listed as the atomic weight of this element?

Snehil Aggarwal · Accepted Answer

1st isotope of 278u = 25%
2nd isotope of 281u = 38%
3rd isotope of 285u = 37%
average atomic mass = 278 x 25/100 + 281 x 38/100 + 285 x
37/100
= 69 5 + 106 78 + 105 45
= 281 73

Suppose that a new element (E) were discovered that existed as three natural isotopes. 25% of the atoms had a mass of 278, 38% had a mass of 281, and the remainder had a mass of 285. What would be listed as the atomic weight of this element?