Q. A solution has a density of 1.2 g/mL and contains 30 g of solute. What is the molarity if the molar mass of the solute is 60 g/mol?
A.
0.5 M
B.
1 M
C.
2 M
D.
1.5 M
Solution
Volume of solution = mass / density = 30 g / 1.2 g/mL = 25 mL = 0.025 L. Moles of solute = 30 g / 60 g/mol = 0.5 moles. Molarity = 0.5 moles / 0.025 L = 20 M.
Q. A solution is prepared by dissolving 50 g of glucose (C6H12O6) in 250 g of water. What is the mass percent of glucose in the solution? (Molar mass of glucose = 180 g/mol)
A.
20%
B.
15%
C.
25%
D.
10%
Solution
Mass percent = (mass of solute / (mass of solute + mass of solvent)) × 100 = (50 g / (50 g + 250 g)) × 100 = 20%.
Q. A solution is prepared by dissolving 58.5 g of NaCl in 1 L of water. What is the concentration in terms of molarity? (Molar mass of NaCl = 58.5 g/mol)
A.
1 M
B.
2 M
C.
0.5 M
D.
0.25 M
Solution
Moles of NaCl = 58.5 g / 58.5 g/mol = 1 mole. Molarity = 1 mole / 1 L = 1 M.
Q. A solution is prepared by dissolving 58.5 g of NaCl in enough water to make 1 L of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.5 g/mol)
A.
1 M
B.
2 M
C.
0.5 M
D.
0.1 M
Solution
Moles of NaCl = 58.5 g / 58.5 g/mol = 1 mole. Molarity = 1 mole / 1 L = 1 M.
Q. If 10 grams of NaCl is dissolved in 500 mL of water, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
A.
0.34 m
B.
0.17 m
C.
0.85 m
D.
0.50 m
Solution
Molality (m) = moles of solute / kg of solvent. Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of water = 0.5 kg. Molality = 0.171 moles / 0.5 kg = 0.342 m.
Q. If 10 grams of NaCl is dissolved in enough water to make 500 mL of solution, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
A.
0.34 m
B.
0.17 m
C.
0.85 m
D.
0.50 m
Solution
Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of solvent (water) = 0.5 kg. Molality (m) = moles of solute / kg of solvent = 0.171 moles / 0.5 kg = 0.34 m.
Q. If 10 grams of NaOH is dissolved in 500 mL of solution, what is the molality of the solution? (Molar mass of NaOH = 40 g/mol)
A.
0.5 m
B.
1 m
C.
2 m
D.
0.25 m
Solution
Moles of NaOH = 10 g / 40 g/mol = 0.25 moles. Mass of solvent (water) = 0.5 kg. Molality (m) = moles of solute / kg of solvent = 0.25 moles / 0.5 kg = 0.5 m.
Understanding concentration terms is crucial for students preparing for exams, as these concepts frequently appear in various subjects. Practicing MCQs and objective questions on concentration terms not only enhances your grasp of the topic but also boosts your confidence in tackling exam questions. Engaging with practice questions helps identify important questions and solidifies your exam preparation strategy.
What You Will Practise Here
Definitions of concentration terms such as molarity, molality, and normality.
Key formulas related to concentration calculations.
Understanding the differences between various concentration measures.
Real-life applications of concentration concepts in chemistry.
Diagrams illustrating concentration concepts for better visualization.
Sample problems and their step-by-step solutions.
Common units of concentration and their conversions.
Exam Relevance
Concentration terms are a significant part of the curriculum for CBSE, State Boards, NEET, and JEE. Students can expect questions that require them to calculate concentrations, interpret data, or apply concepts to real-world scenarios. Common question patterns include direct calculations, conceptual understanding, and application-based problems, making it essential to master this topic for success in exams.
Common Mistakes Students Make
Confusing molarity with molality and using them interchangeably.
Neglecting to account for temperature changes when calculating concentrations.
Overlooking the significance of units in concentration calculations.
Misinterpreting questions that ask for the concentration of solutions in different contexts.
Failing to practice enough problems, leading to a lack of confidence during exams.
FAQs
Question: What is the difference between molarity and molality? Answer: Molarity is the number of moles of solute per liter of solution, while molality is the number of moles of solute per kilogram of solvent.
Question: How can I improve my understanding of concentration terms? Answer: Regular practice of MCQs and solving objective questions will help reinforce your understanding and application of concentration terms.
Start solving practice MCQs on concentration terms today to test your understanding and enhance your exam readiness. Remember, consistent practice is key to mastering this essential topic!
Soulshift Feedback×
On a scale of 0–10, how likely are you to recommend
The Soulshift Academy?
