Question

The volume of water that would convert 10ml of deca molar HCl solution to deca molar solution is
A. ${{10}^{3}}$ ml
B. ${{10}^{2}}$ ml
C. $9.9 \times {{10}^{3}}$ ml
D. 1.2L

Answer 1

This is a simple question which can be solved just by the basic conversion formula for the volume. We should know the difference between the units of volume like deca, deci, milli, etc to solve this question.

Complete step by step solution:
-There are seven basic quantities named mass, time, temperature, length, electric current, amount of substance and luminous intensity.
-All these quantities have a particular SI unit which is followed by everyone and everywhere. The SI units for the following mentioned quantities are kg, s, K, m, A, mole and candela respectively.
-But due to diversity in the world, there are many other units that are also into use in daily lives. The SI unit for the volume is L but many other units are also used like ml, dl, $c{{m}^{3}},{{m}^{3}}$ , etc.
-Volume is the 3-dimensional measure of the length and gives us the storage capacity of the given structure and so it is found by multiplying the unit of length thrice thus giving us a meter cube.
-In the question we are given the unit to be M for molarity. We know that molarity is the ratio of the moles of the solute to the volume of the solution and can be expressed mathematically as
$molarity=\dfrac{moles\text{ }of\text{ }solute}{volume\text{ of solution}}=\dfrac{mol}{L}$
-Moles/L give us nothing but M only. We are given 10M. It means that we are given 10 moles/L. Also deca signifies 10 and so the final unit can be expressed as
10x10M which when converted into ml gives us
10x10L = Vx11010x10ml=Vx110
So, from this we get V=1000ml.
-We were already given a 10ml solution and now when we add 990ml of HCl, the resulting solution will be 10000 ml which is equivalent to 1L. This value is nothing but ${{10}^{3}}$ ml

Therefore, the correct option is A.

Note: One thing to keep in mind is that the molarity depends on the volume of the solution and not the solvent.
Solution = solute + solvent.
So, in a solution, the volume is added not only by the solvent but also by the solute. There are certain concepts like molality where we need the physical quantities of solvent and not of solution.