Question

What volume of a 0.8 M solution contains 100 millimoles of the solute.
A. 100mL
B. 125mL
C. 500mL
D. 62.5mL

Answer 1

Hint:The mole is the concept which used widely to express the concept of the amount of substance present in the compound. In the field of chemistry we define mole as the amount of substance which tends to contain \[6.023\times {{10}^{23}}\]elementary entities of the given substance. The number written as \[6.023\times {{10}^{23}}\]is known as Avogadro number. The elementary entities can be represented in moles can be molecules, atoms, monatomic ions or other particles.

Complete step-by-step answer:Now to approach this question we need to know the formula for molarity.
So the formula for molarity is= \[\dfrac{moles of solute}{volume of solution(L)}\]
Molarity of solute is = 0.8M
Moles of solute is = 100 millimoles = \[100\times {{10}^{-3}}\]
Let the volume of solution which we need to find be equal to= V
So now substituting the values in the formula we get,
\[0.8M=\dfrac{100\times {{10}^{-3}}}{V}\]
On solving further we get,
V(mL)= \[\dfrac{100\times {{10}^{-3}}}{0.8}=125mL\]
So the volume of the solution in millilitre is 125mL.

So the correct answer for this question is option B.

Note:Molarity is defined as the total moles of the solute present in the per litre of solution. It generally denoted by M. it depends and changes on the changing of the physical properties of the system such as pressure, temperature as unlike mass, volume of the system. The one molar is defined as the molarity of the solution in which one gram of solute is dissolved in a litre of solution.