Answer:
Step-by-step explanation:
To find the percent by mass of copper in the alloy, you can use the following formula:
Percent by mass of copper
=
Mass of copper
Total mass of the alloy
×
100
Percent by mass of copper= 
Total mass of the alloy
Mass of copper
 ×100
You are given that the mass of copper is 8.0 grams, and you want to produce 100 grams of the alloy. Plug these values into the formula:
Percent by mass of copper
=
8.0
 
g
100
 
g
×
100
Percent by mass of copper= 
100g
8.0g
 ×100
Now, calculate the percentage:
Percent by mass of copper
=
8.0
100
×
100
=
8
%
Percent by mass of copper= 
100
8.0
 ×100=8%
So, the percent by mass of copper in the alloy is 8%