Prepare a 1% copper sulfate solution. To make this solution, weigh 1 gram of copper sulfate (CuSO4 ·5H2O), dissolve in a small amount of distilled water in a 100 ml volumetric flask and bring to volume. Label this as 1% copper sulfate solution.
They share four electrons, two from each oxygen atom
Answer:

Explanation:
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In this case, according to the given information, it turns out possible for us to calculate the volume of the new solution by using the general formula of dilution:

In such a way, we solve for the final volume, V2, to obtain:

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I think the answer is (1) Co. Because the element of Cobalt also has 2 electrons at the outer layer which is the same as Calcium. And the outer layer is an important factor which can affect the property of an element.