Answer:
<h2>0.02 moles </h2>
Explanation:
To find the number of moles in a substance given it's number of entities we use the formula

where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
We have

We have the final answer as
<h3>0.02 moles</h3>
Hope this helps you
First, we must find the total mass of CuBr₂:
Mass = 64 + 2 x 80
Mass = 224
Percentage mass of copper = mass of copper x 100 / total mass
Percentage mass of copper = (64 / 224) x 100
Percentage mass of copper = 28.45%