Question

Element X has two isotopes. One isotope has a mass of 15 amu and a percent abundance of 75%. The

other isotope has a mass of 19 amu and a percent abundance of 25%. What is the average atomic mass of Element X?
a. 17
b. 15
c. 19
d. 16
e. 18

Answer 1

To calculate the average atomic mass of element X with two isotopes, multiply the mass of each isotope by its percent abundance. The average atomic mass of element X is approximately 17 amu.

Step-by-step explanation:

To calculate the average atomic mass of element X, we need to multiply the mass of each isotope by its percent abundance. The equation for average atomic mass is:

Average Atomic Mass = (Mass of Isotope 1 * Percent Abundance of Isotope 1) + (Mass of Isotope 2 * Percent Abundance of Isotope 2)

For element X, the average atomic mass would be:

((15 amu * 75%) + (19 amu * 25%)) = 17.25 amu

Therefore, the average atomic mass of element X is approximately 17 amu, so the correct answer is (a) 17.