Answer
The atomic mass of europium is about 152 amu.
Work Step by Step
As we can see on the graph, the abundance of Eu-151 is about 90%, and by its name, the value of its mass is approximately 151 amu.
If we repeat the process for Eu-153, we get an abundance of 100% and a mass of about 153 amu.
- Calculate the atomic mass of europium:
$$atomic \space mass = \frac{(90\% \times 151 \space amu) + (100\% \times 153 \space amu)}{90\% + 100\%} \approx 152 \space amu$$
