CUET UG Chemistry Booster Test - 2 Concentration Measures and Solubility
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QUESTION 1 OF 20
What is the unit of mole fraction, xi?
QUESTION 2 OF 20
In a ternary mixture containing components A, B, and C, if xA = 0.3 and xB = 0.4, what is the value of xC?
QUESTION 3 OF 20
Arrange the following solutions in decreasing order of molarity:
1. 0.5 mol of NaOH in 1.0 L solution
2. 2.0 mol of KCl in 2.0 L solution
3. 0.1 mol of Glucose in 0.5 L solution
4. 1.5 mol of NaCl in 0.5 L solution
QUESTION 4 OF 20
If an aqueous solution is heated from 25°C to 80°C, how will its molarity behave, assuming no solvent evaporates?
QUESTION 5 OF 20
Match the solute amounts with their corresponding molality in 1 kg of water.
| List 1 (Solute Amount) | List 2 (Corresponding Molality) |
|---|---|
| 1. 40 g NaOH | a. 1.0 m |
| 2. 60 g Urea | b. 1.0 m |
| 3. 90 g Glucose | c. 0.5 m |
| 4. 20 g NaOH | d. 0.5 m |
QUESTION 6 OF 20
Why is molality an independent concentration measure in relation to thermal variation?
1. It relates to the volume of the solution directly.
2. Mass is not a function of temperature.
3. Volume is not a function of temperature.
4. It uses moles per litre instead of kilograms.
QUESTION 7 OF 20
Identify the specific term used to refer to the concentration of a solute in a saturated solution at a dynamic equilibrium.
QUESTION 8 OF 20
Which combination is most likely to result in a successful dissolution based on the nature of substances?
QUESTION 9 OF 20
Which principle or rule governs the dissolution of polar solutes in polar solvents and non-polar solutes in non-polar solvents?
QUESTION 10 OF 20
Identify the process type regarding energetic intermolecular dynamics: For a solute to dissolve in a solvent, the interactions must be:
QUESTION 11 OF 20
During the initial stages of adding a solid solute to a pure solvent, which process dominates the system?
QUESTION 12 OF 20
In a saturated solution, if radioactively tagged solute crystals are added, the radioactivity will soon be detected in the liquid phase as well. This proves that:
QUESTION 13 OF 20
A saturated solution's concentration limit is specifically defined by its:
QUESTION 14 OF 20
If a solution is unsaturated, the rate of dissolution compared to the rate of crystallisation is:
QUESTION 15 OF 20
QUESTION 16 OF 20
QUESTION 17 OF 20
The primary reason pressure has minimal effect on the solubility of solids in liquids is because:
QUESTION 18 OF 20
Which equilibrium system is LEAST affected by a change in pressure?
QUESTION 19 OF 20
Which of the following gases is greatly affected by pressure and temperature when dissolved in liquids?
QUESTION 20 OF 20
The dissolved oxygen in aquatic environments sustains life, despite its solubility being:
Test Complete!
Answer Review
1 What is the unit of mole fraction, xi?
�� Mole fraction is a ratio. �� It compares moles of a component with total moles. 1. • Ratios have no unit.
2. → Mole fraction is defined as moles of a component divided by total moles of all components. Since both numerator and denominator have the same unit, the units cancel out. Therefore, mole fraction is dimensionless.
- �� Option A → mol L⁻¹ is the unit of molarity.
- �� Option B → mol kg⁻¹ is the unit of molality.
- 3. • Option D → g mol⁻¹ is the unit of molar mass.
Used
- 4. Dimensional/Unit Analysis
Application:
- �� Compare the units in the numerator and denominator of mole fraction.
Final Logic:
- �� mole/mole cancels, so mole fraction has no unit.
1. → Fraction has no unit.
2 In a ternary mixture containing components A, B, and C, if xA = 0.3 and xB = 0.4, what is the value of xC?
�� Sum of mole fractions is 1. �� xA + xB + xC = 1. 1. • xC = 1 − 0.7 = 0.3.
2. → In any solution, the sum of mole fractions of all components is unity. Here, xA = 0.3 and xB = 0.4. Therefore, xC = 1 − (0.3 + 0.4) = 0.3.
- �� Option A → 0.7 is the sum of xA and xB, not xC.
- �� Option C → 1.0 is the total sum of all mole fractions.
- 3. • Option D → 0.1 is not obtained from the mole fraction relation.
Used
- 4. Substitution
Application:
- �� Substitute given values into xA + xB + xC = 1.
Final Logic:
- �� xC = 1 − 0.3 − 0.4 = 0.3.
1. → Mole fractions make one whole.
3 Arrange the following solutions in decreasing order of molarity:
1. 0.5 mol of NaOH in 1.0 L solution
2. 2.0 mol of KCl in 2.0 L solution
3. 0.1 mol of Glucose in 0.5 L solution
4. 1.5 mol of NaCl in 0.5 L solution
�� Molarity = moles/litre. �� Calculate each molarity first. 1. • Arrange from highest to lowest.
- 1 = 0.5/1.0 = 0.5 M 2 = 2.0/2.0 = 1.0 M 3 = 0.1/0.5 = 0.2 M 2. 4 = 1.5/0.5 = 3.0 M Decreasing order: 4 > 2 > 1 > 3.
- �� Option B → Places 0.5 M before 3.0 M and 1.0 M.
- �� Option C → Places 1.0 M before 3.0 M.
- 1. • Option D → Places 0.2 M before 0.5 M.
Used
- 2. Dimensional/Unit Analysis
Application:
- �� Convert all given values into mol L⁻¹ before comparing.
Final Logic:
- �� 3.0 M > 1.0 M > 0.5 M > 0.2 M.
1. → Calculate before arranging.
4 If an aqueous solution is heated from 25°C to 80°C, how will its molarity behave, assuming no solvent evaporates?
�� Molarity depends on volume. �� Heating expands the solution. 1. • Moles remain constant, so molarity decreases.
2. → Molarity is moles of solute per litre of solution. On heating, the volume of the solution generally increases due to thermal expansion. Since the number of moles remains unchanged, molarity decreases.
- �� Option A → Heating usually increases volume, not decreases it.
- �� Option C → Mass conservation does not make molarity constant because molarity depends on volume.
- 3. • Option D → Mass of solvent does not increase on heating.
Used
- 4. Dimensional/Unit Analysis
Application:
- �� Apply molarity = moles/volume and analyze the effect of increased volume.
Final Logic:
- �� Volume increases, denominator increases, molarity decreases.
1. → Heat ↑, Volume ↑, Molarity ↓.
5 Match the solute amounts with their corresponding molality in 1 kg of water.
| List 1 (Solute Amount) | List 2 (Corresponding Molality) |
|---|---|
| 1. 40 g NaOH | a. 1.0 m |
| 2. 60 g Urea | b. 1.0 m |
| 3. 90 g Glucose | c. 0.5 m |
| 4. 20 g NaOH | d. 0.5 m |
�� 40 g NaOH = 1 mole. �� 60 g urea = 1 mole. 1. • 90 g glucose = 0.5 mole.
- Molality is moles of solute per kg of solvent. Since the solvent is 1 kg water, molality equals the number of moles of solute. 40 g NaOH ÷ 40 = 1.0 m 60 g urea ÷ 60 = 1.0 m 90 g glucose ÷ 180 = 0.5 m 2. 20 g NaOH ÷ 40 = 0.5 m
- �� Option B → Incorrectly matches 40 g NaOH with 0.5 m.
- �� Option C → Incorrectly matches 60 g urea and 20 g NaOH.
- 3. • Option D → Incorrectly matches all calculated molality values.
Used
- 4. Dimensional/Unit Analysis
Application:
- �� Convert grams into moles using molar mass, then divide by 1 kg solvent.
Final Logic:
- �� In 1 kg water, molality = moles of solute.
1. → 1 kg solvent makes m = moles.
6 Why is molality an independent concentration measure in relation to thermal variation?
1. It relates to the volume of the solution directly.
2. Mass is not a function of temperature.
3. Volume is not a function of temperature.
4. It uses moles per litre instead of kilograms.
�� Molality uses mass of solvent. �� Mass does not change with temperature. 1. • Therefore, molality is temperature independent.
2. → Molality is defined as moles of solute per kilogram of solvent. Since it depends on mass and not volume, it remains independent of temperature. Mass is not a function of temperature, but volume is affected by temperature.
- �� Option A → Statements 1 and 3 are incorrect.
- �� Option C → Statement 3 is incorrect because volume changes with temperature.
- 3. • Option D → Both Statements 3 and 4 are incorrect.
Used
- 4. Elimination
Application:
- �� Remove statements involving volume independence or moles per litre.
Final Logic:
- �� Molality is temperature independent because mass is temperature independent.
1. → Molality = mass-based.
7 Identify the specific term used to refer to the concentration of a solute in a saturated solution at a dynamic equilibrium.
�� Saturated solution contains maximum dissolved solute. �� Dynamic equilibrium exists. 1. • This concentration is called solubility.
2. → Solubility is the concentration of solute in a saturated solution at a given temperature and pressure. At saturation, dissolution and crystallisation occur at equal rates, establishing dynamic equilibrium.
- �� Option A → Molality is a concentration unit, not the specific saturated concentration term.
- �� Option B → Molarity is also a concentration unit, not the term for saturated concentration.
- 3. • Option D → Mole fraction is a way of expressing composition, not specifically solubility.
Used
- 4. Contextual/Tonal Matching
Application:
- �� Link saturated solution concentration with the term used in NCERT.
Final Logic:
- �� Concentration of saturated solution = solubility.
1. → Saturated concentration = solubility.
8 Which combination is most likely to result in a successful dissolution based on the nature of substances?
�� Benzene is non-polar. �� Naphthalene is non-polar. 1. • Like dissolves like.
2. → A solute dissolves best in a solvent having similar intermolecular interactions. Naphthalene is non-polar and benzene is also non-polar, so naphthalene dissolves readily in benzene.
- �� Option A → Sodium chloride is ionic and does not dissolve well in non-polar benzene.
- �� Option B → Anthracene is non-polar and does not dissolve well in polar water.
- 3. • Option C → Sugar is polar and does not dissolve well in non-polar benzene.
Used
- 4. Odd One Out
Application:
- �� Identify the pair with similar polarity and intermolecular interactions.
Final Logic:
- �� Non-polar naphthalene dissolves in non-polar benzene.
1. → Like dissolves like.
9 Which principle or rule governs the dissolution of polar solutes in polar solvents and non-polar solutes in non-polar solvents?
�� Polar dissolves polar. �� Non-polar dissolves non-polar. 1. • This is called like dissolves like.
2. → The principle "like dissolves like" explains that substances with similar intermolecular interactions dissolve in each other. Polar solutes dissolve in polar solvents, while non-polar solutes dissolve in non-polar solvents.
- �� Option A → Henry's law deals with solubility of gases in liquids.
- �� Option B → Le Chatelier's principle explains equilibrium shifts.
- 3. • Option D → Raoult's law relates vapour pressure to mole fraction.
Used
- 4. Contextual/Tonal Matching
Application:
- �� Match the phrase about polar-polar and non-polar-non-polar dissolution.
Final Logic:
- �� Similar nature supports dissolution.
1. → Like likes like.
10 Identify the process type regarding energetic intermolecular dynamics: For a solute to dissolve in a solvent, the interactions must be:
�� Similar intermolecular interactions favour dissolution. �� Solute-solvent attraction must be effective. 1. • This supports solution formation.
2. → For dissolution to occur, solute-solvent interactions must be similar or comparable to the interactions present among solute-solute and solvent-solvent particles. This is the basis of the "like dissolves like" principle.
- �� Option A → Dissolution is not exclusively ionic; covalent and non-polar substances may also dissolve.
- �� Option C → If solute-solute interactions dominate strongly, dissolution becomes difficult.
- 3. • Option D → Repulsive interactions prevent dissolution.
Used
- 4. Elimination
Application:
- �� Remove extreme or scientifically incorrect conditions.
Final Logic:
- �� Similar interactions between solute and solvent favour dissolution.
1. → Similar forces mix.
11 During the initial stages of adding a solid solute to a pure solvent, which process dominates the system?
Initially, only solvent is present. Solute particles begin entering the solvent. Dissolution rate is greater than crystallisation.
- When a solid solute is first added to a pure solvent, there are almost no dissolved solute particles available to undergo crystallisation. Therefore, dissolution dominates the system, increasing the solute concentration until saturation is approached. Only after sufficient solute dissolves does crystallisation begin to compete with dissolution.
- Option A → Crystallisation requires dissolved solute particles and does not dominate initially.
- Option C → Precipitation is the formation of an insoluble solid from a reaction and is not the process occurring here.
- Option D → Sublimation is the direct conversion of a solid into a gas and is unrelated to solution formation.
Used
- Contextual/Tonal Matching
Application:
- �� Focus on the phrase "initial stages", where dissolution naturally exceeds crystallisation.
Final Logic:
- �� Pure solvent + added solute = dissolution dominates.
Start = Dissolve First
12 In a saturated solution, if radioactively tagged solute crystals are added, the radioactivity will soon be detected in the liquid phase as well. This proves that:
Solute particles continuously exchange. Both processes occur simultaneously. Dynamic equilibrium exists.
- The movement of radioactive particles from the crystal into the solution demonstrates that solute particles continuously dissolve while an equal number simultaneously crystallise. Although there is no net change in concentration, both processes continue at equal rates, proving the existence of dynamic equilibrium.
- Option A → The solution remains saturated despite particle exchange.
- Option B → Crystallisation continues at the same rate as dissolution.
- Option D → Radioactivity acts only as a tracer and does not change solubility.
Used
- Contextual/Tonal Matching
Application:
- �� Interpret the tracer experiment using the concept of dynamic equilibrium.
Final Logic:
- �� Particle exchange without concentration change indicates dynamic equilibrium.
Dynamic = Both Directions Continue
13 A saturated solution's concentration limit is specifically defined by its:
Saturated solution contains maximum dissolved solute. Maximum concentration is called solubility. It depends on temperature.
- Solubility is defined as the maximum amount of solute that can dissolve in a specified amount of solvent at a given temperature and pressure. Therefore, the concentration limit of a saturated solution is its solubility.
- Option A → Molality is only a concentration unit and does not define the saturation limit.
- Option B → Saturation index is not the NCERT definition of concentration limit.
- Option D → Osmotic point is unrelated to saturation concentration.
Used
- Odd One Out
Application:
- �� Identify the NCERT term specifically defining the saturation concentration.
Final Logic:
- �� Saturated concentration = Solubility.
Saturated = Solubility Limit
14 If a solution is unsaturated, the rate of dissolution compared to the rate of crystallisation is:
More solute can still dissolve. Dissolution exceeds crystallisation. Concentration continues increasing.
- In an unsaturated solution, the solvent can still accommodate additional solute particles. Therefore, the rate of dissolution is greater than the rate of crystallisation, resulting in a net increase in dissolved solute concentration until saturation is reached.
- Option A → Dissolution is not slower than crystallisation in an unsaturated solution.
- Option B → Equal rates occur only at dynamic equilibrium in a saturated solution.
- Option D → Crystallisation is not necessarily zero; however, dissolution predominates.
Used
- Elimination
Application:
- �� Eliminate options describing saturated equilibrium or impossible conditions.
Final Logic:
- �� Unsaturated solution → Dissolution > Crystallisation.
Unsaturated = Dissolve More
15
Endothermic dissolution absorbs heat. Heating supplies additional heat. Solubility increases.
- An endothermic dissolution process absorbs heat from the surroundings. According to Le Chatelier's Principle, increasing the temperature supplies additional heat and shifts the equilibrium toward dissolution, thereby increasing the solubility of the solid.
- Option A → Lowering temperature shifts equilibrium away from dissolution.
- Option B → Pressure has negligible effect on the solubility of solids in liquids.
- Option D → Decreasing pressure does not significantly affect solid-liquid solubility.
Used
- Contextual/Tonal Matching
Application:
- �� Use the passage statement "endothermic dissolution increases with rise in temperature."
Final Logic:
- �� Endothermic process + Heat added = Greater solubility.
Endothermic Loves Heat
16
Exothermic dissolution releases heat. Heating opposes the dissolution process. Solubility decreases.
- According to Le Chatelier's Principle, heat acts as a product in an exothermic dissolution process. When the temperature is increased, the equilibrium shifts in the reverse direction to consume the added heat, resulting in less solute dissolving and hence a decrease in solubility.
- Option A → Heating favors dissolution only in endothermic processes.
- Option C → Heating does not produce additional solvent.
- Option D → Solubility cannot become infinite.
Used
- Contextual/Tonal Matching
Application:
- �� Apply Le Chatelier's Principle to an exothermic dissolution equilibrium.
Final Logic:
- �� Heat added + exothermic process = decreased solubility.
Exothermic Hates Heat
17 The primary reason pressure has minimal effect on the solubility of solids in liquids is because:
Solids and liquids show negligible compression. Pressure causes very little volume change. Solubility remains almost unchanged.
- Pressure significantly affects gases because gases are highly compressible. Solids and liquids, however, are highly incompressible, so increasing pressure produces only a negligible change in their volume. Consequently, pressure has almost no effect on the solubility of solids in liquids.
- Option A → Solids and liquids do not undergo rapid expansion under pressure.
- Option B → They are incompressible, not highly compressible.
- Option D → Liquids do not instantly vaporize under high pressure.
Used
- Elimination
Application:
- �� Eliminate statements contradicting the physical properties of solids and liquids.
Final Logic:
- �� Incompressibility explains the negligible pressure effect.
Solid + Liquid = Pressure Little
18 Which equilibrium system is LEAST affected by a change in pressure?
Solids and liquids are nearly incompressible. Pressure has negligible influence. Solid-liquid equilibrium remains almost unchanged.
- Pressure mainly affects systems involving gases because gases undergo significant volume changes. A solid dissolved in a liquid involves two incompressible phases, so pressure produces almost no change in equilibrium or solubility.
- Option A → Gas solubility in liquids increases with pressure (Henry's Law).
- Option C → Gas-phase equilibria are strongly influenced by pressure.
- Option D → Liquid-vapour equilibrium is also pressure dependent.
Used
- Odd One Out
Application:
- �� Identify the equilibrium system without a gaseous phase.
Final Logic:
- �� No gaseous phase = least pressure effect.
No Gas = No Pressure Effect
19 Which of the following gases is greatly affected by pressure and temperature when dissolved in liquids?
Gas solubility changes with pressure. Gas solubility also changes with temperature. Both factors are important.
- Unlike solids, the solubility of gases in liquids depends significantly on both pressure and temperature. According to Henry's Law, increasing pressure generally increases gas solubility, while increasing temperature usually decreases the solubility of gases in liquids.
- Option A → Pressure also significantly affects gas solubility.
- Option B → Temperature also significantly affects gas solubility.
- Option C → Gas solubility is influenced by both variables.
Used
- Elimination
Application:
- �� Remove options considering only one variable or none.
Final Logic:
- �� Gas solubility depends on both pressure and temperature.
Gas = Pressure + Temperature
20 The dissolved oxygen in aquatic environments sustains life, despite its solubility being:
Oxygen is only sparingly soluble. Even small dissolved amounts support aquatic respiration. Aquatic ecosystems depend on this dissolved oxygen.
- Oxygen dissolves in water only to a small extent, yet this dissolved oxygen is sufficient to sustain fish and other aquatic organisms through respiration. Its concentration is limited but biologically essential.
- Option A → Oxygen is not highly soluble in water.
- Option C → Oxygen does not react with water to form an acid under normal conditions.
- Option D → The solubility of gases, including oxygen, is affected by pressure.
Used
- Odd One Out
Application:
- �� Compare the known physical properties of dissolved oxygen with the given statements.
Final Logic:
- �� Aquatic life survives on oxygen that is dissolved only to a small extent.
Small O₂, Big Life
