Question

boron isotopes are 19.9% boron -10, 80.1%, boron -11. calculate the average atomic mass of boron.

Explanation:

Step1: Identify the formula

The formula for average atomic mass is $Average\ atomic\ mass=\sum_{i} (Relative\ abundance_i\times Mass_i)$.

Step2: Substitute the values

Boron - 10 has a mass of 10 amu and relative abundance of 0.199; boron - 11 has a mass of 11 amu and relative abundance of 0.801. So, $Average\ atomic\ mass=(0.199\times10)+(0.801\times11)$.

Step3: Calculate the result

First, $0.199\times10 = 1.99$. Second, $0.801\times11=8.811$. Then, $1.99 + 8.811=10.801$ amu.

Answer:

10.801 amu