Asolution is prepared by dissolving 20.1 g of mgcl2 with the addition of 157.0 ml of water (density of water is 1.00g/cm3). the density of the resulting solution was determined to be 1.089g/cm3. calculate the molar concentration of this solution: hint: make sure you understand the definition on molar concentration

1.3 M.

Explanation:

mass of the solution = mass of MgCl₂ + mass of water

mass of MgCl₂ = 20.1 g.

mass of water = d.V = (157.0 mL)(1.0 g/cm³) = 157.0 g.

∴ mass of the solution = mass of MgCl₂ + mass of water = 20.1 g + 157.0 g = 177.1 g.

V of the solution = (mass of the solution)/(density of the solution) = (177.1 g)/(1.089 g/cm³) = 162.62 mL = 0.163 L.

Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.

M = (no. of moles of MgCl₂) / (Volume of the solution (L)).

∴ M = (mass/molar mass)of MgCl₂ / (Volume of the solution (L)) = (20.1 g/95.211 g/mol) / (0.163 L) = 1.29 M ≅ 1.3 M.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.