Question

What do you need to know about a stock solution in order to calculate a dilution?
(A) Molarity
(B) Molality
(C) Ppm
(D) Volume
(E) Acid or base

Answer 1

Hint: Dilution is the process by which the concentration of the solute is decreased in the given solution. Dilution is generally carried out by adding the more amount of solvent in the solution, so this will automatically lead to a decrease in the concentration of the solute.

Complete answer:
To answer this question we will learn briefly about each given term of concentration.
Stock solution is actually a solution in a concentrated form which will be diluted further to low concentration for actual practical experiments in the laboratories or industries.
Stock solution is an effective method to save time while performing experiments as one can just dilute the stock and will get the desired concentrated solution.
To make the perfect dilutions using a stock solution, one needs to know about the molarity of the solution.
As this is evident by the formula,
 $M_1{V}_1=M_2{V}_2$
Where, $M_1$ is the molarity of the stock solution?
 $V_1$ Is the volume of the stock solution that is used in performing dilutions?
 $M_2$ Is the molar concentration of the diluted solution?
And $V_2$ is the final volume that will be made after the dilutions
So, we can see from the given above formula that Molarity is an important term of measuring the concentration and is very much useful in the dilutions of the stock solution.
So, the correct answer is A. i.e. Molarity. Therefore, Molarity is needed to know about a stock solution in order to calculate a dilution.

Note:
Molarity can be defined as a moles of solute present per litre of the solution. It is also known as the molar concentration of the solution. Its standard unit is generally depicted by the symbol ${}^{\prime }{M}^{\prime }$ . In the laboratories molarity is used to determine the concentrations of the solute or the solvent.