Cu + S ---> CuS
by reaction 1 mol 1 mol
from the problem 0.25 mol 0.25 mol
0.25 mol Cu
Answer:

Explanation:
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In this case, since perchloric acid is HClO4 and is a strong acid and calcium hypochlorite is Ca(ClO)2, the undergoing molecular chemical reaction turns out:

Thus, since the resulting hypochlorous acid is weak, it does not fully ionize, so it remains unionized, however, we can write the ions for the other species:

Now, we can cancel out the spectator ions, calcium and perchlorate, to obtain:

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Answer:
D is the best choice. Those percentages, are giving you the information about how concentrated are the solutions. As 0.015 is so concentrated, this solution will damage the structures more quickly
Explanation: