Question

The amount of solute required to prepare 10 liters of decimolar solution is:
A. 0.01 mole
B. 0.2 mole
C. 0.05 mole
D. 1.0 mole

Answer 1

Hint:To solve this question we will use the concept of molarity .
Molarity is defined as the number of moles of solute present in the 1 liter of the solution.
Molarity is denoted by ‘M’. to solve this question we should be familiar with mole concepts terms like, moles. Molar mass, etc.

Complete step-by-step solution:As we have to make a deci molar solution.
Decimolar means: $\dfrac{1}{{10}}$molarity of the solution:
$\therefore $We all know that :
Molarity is the number of moles of solute present in 1 litre of solution.
$Molarity(M) = \dfrac{{{\text{number of moles of solute}}}}{{volume{\text{ of the solution}}}}$
Mathematically, $M = \dfrac{n}{V}$
$\therefore $According to question;
Given, M=1/10, V=10 liters
So putting the values of all the variables in molarity equation:
$
  \dfrac{1}{{10}} = \dfrac{n}{{10}} \\
  n = 1 \\
 $
Hence, the number of moles will be 1 mole to make the decimolar solution.

Therefore, the correct answer will be option number D.

Note:Moles: Mole is defined as the given mass of the compound divided by the molar mass of the solute.
Let, m is the mass of a given compound .
And let M is the molar mass of that solute.
Then mathematically,
Number of moles of that solute will be equal to : $\dfrac{m}{M}$