= 24.3
The average atomic mass of X is the <em>weighted average</em> of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its <em>relative importance</em> (i.e., its % abundance).
Thus,
0.790 × 24 u = 18.96 u
0.100 × 25 u = 2.50 u
0.110 × 26 u = <u>2.86 u</u>
TOTAL = 24.3 u
∴ The relative atomic mass of X is 24.3.
B. carbon because it's atomic number is 6
Kc = [H3O+][HCO3-] / [H2CO3]
Remember that Kc is products over reactants. Also, you do not include liquid water in a Kc expression, since liquid water has no concentration.