Answer:
This element is Boron (B) and has an average atomic mass of 10.8109 u
Explanation:
The average mass of an element is calculated by taking the average of the atomic masses of its stable isotopes.
The enitre atomic mass = 100 % or 1
⇒ this consists of 19.91 % atoms with mass 10.01 u
19.91 % = 0.1991
⇒ this consists of 80.09 % atoms with mass 11.01 u
80.09 % = 0.8009
To calculate the mass of this isotope we use the following:
0.1991 * 10.01 + 0.8009 * 11.01 = 10.8109 u
This element is Boron (B) and has an average atomic mass of 10.8109 u
