The atomic mass of element X is 26.9 amu.
Formula for Atomic mass
[tex]Atomic mass=\frac{mass of first isotope\times natural abundance+mass of secondisotope\times natural abundance}{100}[/tex]
m₁=mass of 1st isotope
P₁=%abundance of 1st isotope
m₂=mass of 2nd isotope
p₂=%abundance of 2nd istope
[tex]p_2=100-64.24=35.76[/tex]
Calculate atomic mass of element X as follows:-
[tex]atomic mass=\frac{28\times64.24+25\times35.76}{100} \\=26.9[/tex]
So, the atomic mass of element X is 26.9 amu.
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