Answer: To solve this problem, we can use the concept of the dilution formula:
C1V1 = C2V2
Where:
C1 = initial concentration of the concentrated solution (in M)
V1 = volume of the concentrated solution to be taken (in mL)
C2 = final concentration of the diluted solution (in M)
V2 = final volume of the diluted solution (in mL)
Given:
C1 = 17 M (concentration of the concentrated NH3 solution)
V2 = 500.0 mL (final volume of the diluted solution)
C2 = 0.75 M (final concentration of the diluted NH3 solution)
We need to find V1 (volume of the concentrated NH3 solution to be taken).
Now, let's plug the values into the dilution formula:
17 M x V1 = 0.75 M x 500.0 mL
Solving for V1:
V1 = (0.75 M x 500.0 mL) / 17 M
V1 ≈ 22.06 mL
Rounded to the nearest whole number, V1 is approximately 22 mL.
So, the correct answer is (b) 22 mL.