Question

What do you mean by “concentration” of a substance?
A. It is the measure of undissolved substances.
B. It refers to the impurities.
C. Concentration refers to the amount of substance per defined space.
D. It means the total mass of the undissolved gases.

Answer 1

Hint: The term concentration refers to the amount of substance present in a defined volume of space. The space can be solid, liquid and gaseous. In qualitative analysis of compounds or elements we generally use the definition of amount of substance in a solvent or a given solution or the total volume of the mixture of solute and solvent.

Complete step by step answer:
The term ‘’concentration” can be defined qualitatively as the amount of solute particles present in a fixed volume of mixture. If a solution is said to be concentrated, it means that the number of solute particles in a defined space is very high. If the solution is said to be dilute, it means that the number / amount of particles in the fixed volume of space is very less. In order to concentrate a solution, one must add more solute particles in it and in order to dilute the solution, one must add more solvent in the mixture. There are many concentration terms that we use in our day to day lives such as molarity, molality and normality. Molarity is defined as the number of moles of solute per liter of the solution. Molality is defined as the number of moles of solute per kilogram of solvent. Normality is defined as the number of gram equivalents of solute present per liter of the solution.

So, the correct answer is Option C.

Note:
 If we keep adding the solute particles in a solvent to give a solution, there comes a point where no more solute can get dissolved in the solvent. This point where the concentration of the solute is the maximum is known as the saturation point of the solution.