Calculate the atomic mass of element X if there are two isotopes of this element (X-24 and X-28) and 75% of all X atoms are X-28 isotopes.

52 amu

4 amu

27 amu

26 amu

Atomic mass = 27 amu

Explanation:

Given dа ta:

Atomic mass of element X=?

Abundance of X-28 = 75%

Abundance of X-24 = 100 - 75 = 25%

Atomic mass of X-28 = 28 amu

Atomic mass of X-24 = 24 amu

Solution:

Average atomic mass = (abundance of 1st isotope * its atomic mass) + (abundance of 2nd isotope * its atomic mass) / 100

Average atomic mass = (75*28) + (25*24) / 100

Average atomic mass = 2100 + 600 / 100

Average atomic mass = 2700 / 100

Average atomic mass = 27 amu.