Answer : The correct option is, 0.21 moles
Solution : Given,
Molarity of the solution = 0.85 M = 0.85 mole/L
Volume of solution = 250 ml = 0.25 L [tex](1L=1000ml)[/tex]
Molarity : It is defined as the number of moles of solute present in one liter of the solution.
Formula used :
[tex]Molarity=\frac{\text{moles of solute}}{\text{Volume of solution in liters}}[/tex]
Now put all the given values in this formula, we get the moles of solute of the solution.
[tex]0.85mole/L=\frac{\text{moles of solute}}{0.25L}[/tex]
[tex]\text{moles of solute}=0.2125=0.21moles[/tex]
Therefore, the moles of solute is, 0.21 moles
Answer: Option (b) is the correct answer.
Explanation:
It is known that molarity is the number of moles present in liter of solution.
Mathematically, Molarity = [tex]\frac{\text{no. of moles}}{\text{volume in liter}}[/tex]
It is given that volume is 250 mL or volume in liter will be 0.25 L (as 1 L = 1000 mL) and molarity is given as 0.85 M.
Therefore, calculate the number of moles of the solute as follows.
Molarity = [tex]\frac{\text{no. of moles}}{\text{volume in liter}}[/tex]
0.85 M = [tex]\frac{\text{no. of moles}}{0.25 L}[/tex]
no. of moles = 0.21 mol
Therefore, we can conclude that 0.21 moles of solute are contained in a 250.0-milliliter solution that has a concentration of 0.85 M.
