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)
Specific heat capacity= Quantity of heat/massxΔT
Shc of iron (constant)= 0.4494J/³C for 1g
1.49kg=1490g
Q=1490x(22-155)x0.4494
Q=<span>89057.598J</span>
Economic concerns is the correct one
Electronegativity is related to covalent bonding because when two atoms have the same electronegativity bond, they will form a pure covalent bond.
Ba²⁺ + 2Cl⁻ + 2H⁺ + SO₄²⁻ = BaSO₄ (precipitate) + 2H⁺ + 2Cl⁻
Ba²⁺ + SO₄²⁻ = BaSO₄