Molar concentration of a solution of water is:(a) Always equal to normality(b) More than molality of the solution(c) Equal to molality of the solution(d) Less than molality of the solution

The molar concentration of a solution, also known as molarity, is defined as the amount of solute (in moles) divided by the volume of the solution (in liters). On the other hand, molality refers to the amount of solute (in moles) divided by the mass of the solvent (in kilograms).

Given this information, we can address the options:

(a) The molar concentration of a solution is not always equal to normality. Normality is a different concentration unit that takes into account the equivalent weight of a solute, which is related to its chemical reactivity. Normality is calculated by dividing the number of equivalents of solute by the volume of the solution in liters.

(b) The molar concentration of a solution can be more or less than the molality of the solution, depending on the density of the solvent. Molality is determined by the mass of the solvent, not the volume. If the density of the solvent is less than 1 g/mL, the molar concentration will be greater than the molality, and vice versa.

(c) The molar concentration of a solution may or may not be equal to the molality of the solution. As mentioned earlier, it depends on the density of the solvent. If the density is 1 g/mL, then the molar concentration and molality will be numerically equal.

(d) The molar concentration of a solution can be less than the molality of the solution when the density of the solvent is greater than 1 g/mL. In such cases, the molar concentration will be lower than the molality.

Therefore, the correct option is:

(d) Less than molality of the solution