To do this, you would first add together the molar mass of all involved elements, to find how many grams are in a mole of Cu(OH)2. Keep in mind, the molar mass is equal to the atomic mass of an element in grams. For example the molar mass of copper (Cu) would be 63.55 (with 2 sig. figs.)
Therefore, now we add together the mass of all elements involved.
Cu: (63.55)+O2(15.99x2=31.98)+H2(1.01x2=2.02)
63.55+31.98+2.02= 97.55g per mole of Cu(OH)2.
Now, divide what we have by how much it takes to get a mole of the stuff.
68.1/97.55= 0.698mol Cu(OH)2
They're elements. Elements are the simplest form of any substance that cannot be broken down by any chemical methods, including electrolysis or even heat. Examples include oxygen, hydrogen etc.
I think it would be C) The surrounding soil can become very fertile
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