There are several various of expressing concentration. For instance, mass percent, volume percent, Molarity, Normality, Molality, etc.
In present case, weight of solute and solvent are given, so it will be convenient to express concentration in terms of mass percent.
Given: weight of solute (Ca2+) = 8500 g
weight of solvent (water) = 490 g.
Therefore, mass of solution = 8500 + 490 = 8990 g
Now, mass percent =

=

= 94.55 %
Answer: Concentration of calcium ions is in this solution is 94.55 % (w/W)
The chemical formula for carbon dioxide is CO2, hope this helps.
Answer:
see below
Explanation:
The rate constant is missing in question, but use C(final) = C(initial)e^-kt = 0.200M(e^-k·10). Fill in k and compute => remaining concentration of reactant
A. immigration, how is this chemistry?