Question

HELP PLEASE URGENT A fictitious element X is composed of 70.0 percent of the isotope X^55, 20.0 percent of the isotope X^ 56, and 10.0 percent of the isotope X^57. Calculate the weighted atomic mass of element X to the nearest tenth. You must show all of your work to earn credit.

Answer 1

Here is a attached solution... Check out image

Answer 2

So according to the question, among random 100 X atoms,

70 will be of atomic mass 55 amu, 20 will be 56 amu and 10 will be 57 amu.

Thus, the average atomic mass of element X =

[(70 x 55)+(20 x 56)+(10 x 57)]/100

= 5540/100

= 55.4

Atomic mass of element X is 55.4 amu.