Questions About Molarity
Multiple-Choice Questions – Molarity
1. What does molarity (M) represent?
A) Grams of solute per liter of solvent
B) Liters of solution per mole of solute
C) Moles of solute per liter of solution
D) Moles of solute per gram of solution
E) Grams of solute per milliliter of solution
2. Which of the following is the correct unit for molarity?
A) mol/kg
B) g/L
C) mol/L
D) mol/mL
E) L/mol
3. If you dissolve 1 mole of NaCl in 1 liter of water, what is the molarity?
A) 0.5 M
B) 1 M
C) 2 M
D) 0.1 M
E) 10 M
4. To prepare a 0.5 M NaCl solution in 1 liter of water, how many moles of NaCl are needed?
A) 0.25
B) 0.5
C) 1
D) 2
E) 5
5. How many grams of NaCl (molar mass = 58.5 g/mol) are needed to make 2 liters of 1 M solution?
A) 29.25 g
B) 58.5 g
C) 117 g
D) 175.5 g
E) 14.6 g
6. What is the molarity of a solution with 2 moles of solute in 500 mL of solution?
A) 0.25 M
B) 0.5 M
C) 2 M
D) 4 M
E) 1 M
7. If 0.25 moles of KCl are dissolved in 0.5 liters of solution, the molarity is:
A) 0.125 M
B) 0.5 M
C) 1 M
D) 2 M
E) 0.25 M
8. What volume of 2 M solution contains 1 mole of solute?
A) 0.25 L
B) 0.5 L
C) 1 L
D) 2 L
E) 3 L
9. Which combination results in a 1 M solution?
A) 2 moles in 1 L
B) 1 mole in 1 L
C) 1 mole in 2 L
D) 0.5 moles in 0.5 L
E) B and D
10. What happens to molarity if water is added to a solution (dilution)?
A) It increases
B) It remains the same
C) It decreases
D) It doubles
E) It becomes zero
11. What is the molarity if 0.75 moles of solute are dissolved in 1.5 liters of solution?
A) 0.25 M
B) 0.5 M
C) 1 M
D) 2 M
E) 1.5 M
12. What is the molarity of a 500 mL solution containing 49 g of H₂SO₄ (molar mass = 98 g/mol)?
A) 0.25 M
B) 0.5 M
C) 1 M
D) 2 M
E) 4 M
13. To prepare 250 mL of a 0.1 M NaOH solution, how many moles of NaOH are needed?
A) 0.01
B) 0.025
C) 0.05
D) 0.1
E) 0.25
14. Which is not needed to calculate molarity?
A) Volume of solution
B) Mass of solute
C) Temperature
D) Molar mass of solute
E) Amount of solute in moles
15. A solution is made by dissolving 0.2 moles of solute in 400 mL of water. The molarity is:
A) 0.4 M
B) 0.5 M
C) 0.6 M
D) 0.8 M
E) 1.0 M
16. What is the molarity of a solution made by dissolving 12 g of NaOH (molar mass = 40 g/mol) in 500 mL?
A) 0.3 M
B) 0.5 M
C) 0.6 M
D) 1 M
E) 1.5 M
17. If 0.1 moles of HCl are present in 250 mL of solution, the molarity is:
A) 0.1 M
B) 0.25 M
C) 0.4 M
D) 0.5 M
E) 1 M
18. What is the volume required to prepare a 0.2 M solution using 0.1 moles of solute?
A) 100 mL
B) 200 mL
C) 300 mL
D) 400 mL
E) 500 mL
19. Which solution has the highest concentration?
A) 1 mole in 2 L
B) 2 moles in 3 L
C) 0.5 moles in 1 L
D) 2 moles in 1 L
E) 3 moles in 5 L
20. What is the molarity of a solution made with 0.9 g of glucose (molar mass = 180 g/mol) in 100 mL?
A) 0.005 M
B) 0.01 M
C) 0.02 M
D) 0.05 M
E) 0.1 M
- Questions on Solute-Solvent Combinations
- Questions on Saturated and Unsaturated Solutions
- Questions on Solubility and Henry's Law of Solubility
Answer Key with Explanations
1. C – Molarity is moles of solute per liter of solution.
2. C – The unit of molarity is mol/L.
3. B – 1 mole in 1 liter = 1 M.
4. B – M = mol/L → mol = 0.5 × 1 = 0.5 mol.
5. C – 2 mol × 58.5 g/mol = 117 g.
6. D – 2 mol / 0.5 L = 4 M.
7. B – 0.25 mol / 0.5 L = 0.5 M.
8. B – 1 mol / 2 M = 0.5 L.
9. E – Both B (1 mol in 1 L) and D (0.5 mol in 0.5 L) give 1 M.
10. C – Adding water dilutes the solution, so molarity decreases.
11. B – 0.75 mol / 1.5 L = 0.5 M.
12. C – 49 g / 98 g/mol = 0.5 mol → 0.5 mol / 0.5 L = 1 M.
13. B – 0.1 M × 0.25 L = 0.025 mol.
14. C – Temperature is not used in the basic molarity formula.
15. B – 0.2 mol / 0.4 L = 0.5 M.
16. C – 12 g / 40 g/mol = 0.3 mol → 0.3 mol / 0.5 L = 0.6 M.
17. B – 0.1 mol / 0.25 L = 0.4 M.
18. E – 0.1 mol / 0.2 M = 0.5 L = 500 mL.
19. D – 2 mol / 1 L = 2 M, the highest.
20. B – 0.9 g / 180 = 0.005 mol → 0.005 mol / 0.1 L = 0.05 M.
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