Class 12 Chemistry – Chapter 1: Solutions (All MCQs)

1. What is the mass percentage of benzene ($\text{C}_6\text{H}_6$) if $22\text{ g}$ of benzene is dissolved in $122\text{ g}$ of carbon tetrachloride ($\text{CCl}_4$)?

A) $84.72\%$
B) $15.28\%$
C) $18.03\%$
D) $22.00\%$

Correct Answer: B) $15.28\%$

2. What is the mole fraction of benzene in a solution containing $30\%$ by mass in carbon tetrachloride?

A) $0.458$
B) $0.542$
C) $0.384$
D) $0.154$

Correct Answer: A) $0.458$

3. What is the molarity of a solution prepared by dissolving $30\text{ g}$ of $\text{Co(NO}_3\text{)}_2 \cdot 6\text{H}_2\text{O}$ in $4.3\text{ L}$ of solution?

A) $0.050\text{ M}$
B) $0.023\text{ M}$
C) $0.103\text{ M}$
D) $0.030\text{ M}$

Correct Answer: B) $0.023\text{ M}$

4. What is the molarity of $30\text{ mL}$ of $0.5\text{ M }\text{H}_2\text{SO}_4$ diluted to $500\text{ mL}$?

A) $0.03\text{ M}$
B) $0.05\text{ M}$
C) $0.15\text{ M}$
D) $0.015\text{ M}$

Correct Answer: A) $0.03\text{ M}$

5. What mass of urea ($\text{NH}_2\text{CONH}_2$) is required in making $2.5\text{ kg}$ of a $0.25\text{ molal}$ aqueous solution?

A) $15\text{ g}$
B) $30\text{ g}$
C) $37\text{ g}$
D) $60\text{ g}$

Correct Answer: C) $37\text{ g}$

6. If the density of a $20\%$ (mass/mass) aqueous $\text{KI}$ solution is $1.202\text{ g mL}^{-1}$, what is its molality?

A) $1.45\text{ m}$
B) $1.51\text{ m}$
C) $0.0263\text{ m}$
D) $1.20\text{ m}$

Correct Answer: B) $1.51\text{ m}$

7. If the solubility of toxic gas $\text{H}_2\text{S}$ in water at STP is $0.195\text{ m}$, what is the Henry’s law constant ($K_H$)?

A) $282\text{ bar}$
B) $195\text{ bar}$
C) $0.0035\text{ bar}$
D) $55.56\text{ bar}$

Correct Answer: A) $282\text{ bar}$

8. Henry’s law constant for $\text{CO}_2$ in water is $1.67 \times 10^8\text{ Pa}$ at $298\text{ K}$. What quantity of $\text{CO}_2$ is present in $500\text{ mL}$ of soda water packed under $2.5\text{ atm }\text{CO}_2$ pressure?

A) $0.042\text{ g}$
B) $1.848\text{ g}$
C) $2.533\text{ g}$
D) $0.0015\text{ g}$

Correct Answer: B) $1.848\text{ g}$

9. Vapour pressure of pure liquids A and B are $450\text{ mm Hg}$ and $700\text{ mm Hg}$ respectively at $350\text{ K}$. If total vapour pressure is $600\text{ mm Hg}$, what is the mole fraction of liquid A in the liquid mixture?

A) $0.6$
B) $0.4$
C) $0.3$
D) $0.7$

Correct Answer: B) $0.4$

10. Vapour pressure of pure water at $298\text{ K}$ is $23.8\text{ mm Hg}$. When $50\text{ g}$ of urea is dissolved in $850\text{ g}$ of water, what is the relative lowering of vapour pressure?

A) $0.0173$
B) $23.4$
C) $0.83$
D) $0.050$

Correct Answer: A) $0.0173$

11. How much sucrose ($\text{C}_{12}\text{H}_{22}\text{O}_{11}$) must be added to $500\text{ g}$ of water to boil at $100^\circ\text{C}$ if it normally boils at $99.63^\circ\text{C}$ at $750\text{ mm Hg}$ ($K_b = 0.52\text{ K kg mol}^{-1}$)?

A) $342.00\text{ g}$
B) $121.67\text{ g}$
C) $0.37\text{ g}$
D) $500.00\text{ g}$

Correct Answer: B) $121.67\text{ g}$

12. What mass of ascorbic acid ($\text{C}_6\text{H}_8\text{O}_6$) is needed in $75\text{ g}$ of acetic acid to lower its melting point by $1.5^\circ\text{C}$ ($K_f = 3.9\text{ K kg mol}^{-1}$)?

A) $5.08\text{ g}$
B) $1.50\text{ g}$
C) $176.00\text{ g}$
D) $3.90\text{ g}$

Correct Answer: A) $5.08\text{ g}$

13. Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving $1.0\text{ g}$ of polymer (molar mass $185,000\text{ g mol}^{-1}$) in $450\text{ mL}$ of water at $37^\circ\text{C}$.

A) $31\text{ Pa}$
B) $310\text{ Pa}$
C) $185\text{ Pa}$
D) $8.314\text{ Pa}$

Correct Answer: A) $31\text{ Pa}$

14. Which of the following is an example of a solid solution in which the solute is a gas?

A) Solution of ethanol in water
B) Solution of copper in gold
C) Solution of hydrogen in palladium
D) Oxygen mixed with nitrogen gas

Correct Answer: C) Solution of hydrogen in palladium

15. What is the molarity of a concentrated nitric acid sample ($68\%$ $\text{HNO}_3$ by mass) with a density of $1.504\text{ g mL}^{-1}$?

A) $16.23\text{ M}$
B) $1.079\text{ M}$
C) $68.00\text{ M}$
D) $15.04\text{ M}$

Correct Answer: A) $16.23\text{ M}$

16. What volume of $0.1\text{ M }\text{HCl}$ is required to react completely with a $1\text{ g}$ equimolar mixture of $\text{Na}_2\text{CO}_3$ and $\text{NaHCO}_3$?

A) $159\text{ mL}$
B) $100\text{ mL}$
C) $106\text{ mL}$
D) $84\text{ mL}$

Correct Answer: A) $159\text{ mL}$

17. A solution is obtained by mixing $300\text{ g}$ of a $25\%$ solution and $400\text{ g}$ of a $40\%$ solution by mass. What is the mass percentage of solute in the resulting solution?

A) $33.57\%$
B) $66.43\%$
C) $35.00\%$
D) $23.50\%$

Correct Answer: A) $33.57\%$

18. What is the molality of an antifreeze solution prepared from $222.6\text{ g}$ of ethylene glycol ($\text{C}_2\text{H}_6\text{O}_2$) and $200\text{ g}$ of water?

A) $17.95\text{ m}$
B) $9.11\text{ m}$
C) $3.59\text{ m}$
D) $6.20\text{ m}$

Correct Answer: A) $17.95\text{ m}$

19. If a water sample is contaminated with chloroform ($\text{CHCl}_3$) at a level of $15\text{ ppm}$ by mass, what is its molality?

A) $1.26 \times 10^{-4}\text{ m}$
B) $1.5 \times 10^{-3}\text{ m}$
C) $1.195 \times 10^{-3}\text{ m}$
D) $1.26 \times 10^{-3}\text{ m}$

Correct Answer: A) $1.26 \times 10^{-4}\text{ m}$

20. What happens to the solubility of gases in liquids as temperature increases?

A) Increases because dissolution is endothermic
B) Decreases because dissolution is exothermic
C) Remains unchanged
D) Increases exponentially

Correct Answer: B) Decreases because dissolution is exothermic

21. Solutions exhibiting positive deviations from Raoult’s law show:

A) $\Delta_{\text{sol}} H < 0$
B) $\Delta_{\text{sol}} H > 0$ (Absorption of heat)
C) $\Delta_{\text{sol}} H = 0$
D) Decrease in total vapour pressure

Correct Answer: B) $\Delta_{\text{sol}} H > 0$ (Absorption of heat)

22. An aqueous solution of a $2\%$ non-volatile solute exerts a pressure of $1.004\text{ bar}$ at the normal boiling point of water ($1.013\text{ bar}$). What is the molar mass of the solute?

A) $41.35\text{ g mol}^{-1}$
B) $18.00\text{ g mol}^{-1}$
C) $98.00\text{ g mol}^{-1}$
D) $40.00\text{ g mol}^{-1}$

Correct Answer: A) $41.35\text{ g mol}^{-1}$

23. What is the vapour pressure of a $1\text{ molal}$ solution of a non-volatile solute in water at $300\text{ K}$ if pure water has a vapour pressure of $12.3\text{ kPa}$?

A) $12.08\text{ kPa}$
B) $12.30\text{ kPa}$
C) $0.217\text{ kPa}$
D) $11.50\text{ kPa}$

Correct Answer: A) $12.08\text{ kPa}$

24. What is the mass of a non-volatile solute (molar mass $= 40\text{ g mol}^{-1}$) required to be dissolved in $114\text{ g}$ of octane to reduce its vapour pressure to $80\%$?

A) $10\text{ g}$
B) $8\text{ g}$
C) $4\text{ g}$
D) $12\text{ g}$

Correct Answer: B) $8\text{ g}$

25. A solution containing $30\text{ g}$ of non-volatile solute in $90\text{ g}$ water has a vapour pressure of $2.8\text{ kPa}$. Adding $18\text{ g}$ of water changes it to $2.9\text{ kPa}$. What is the molar mass of the solute?

A) $23\text{ g mol}^{-1}$
B) $34\text{ g mol}^{-1}$
C) $40\text{ g mol}^{-1}$
D) $18\text{ g mol}^{-1}$

Correct Answer: A) $23\text{ g mol}^{-1}$

26. A $5\%$ solution of cane sugar (molar mass $342\text{ g mol}^{-1}$) freezes at $271\text{ K}$. What is the freezing point of a $5\%$ glucose solution (molar mass $180\text{ g mol}^{-1}$) in water? (Freezing point of pure water $= 273.15\text{ K}$)

A) $269.06\text{ K}$
B) $271.00\text{ K}$
C) $273.15\text{ K}$
D) $265.50\text{ K}$

Correct Answer: A) $269.06\text{ K}$

27. Compounds $\text{AB}_2$ and $\text{AB}_4$ dissolved in $20\text{ g}$ benzene lower the freezing point by $2.3\text{ K}$ and $1.3\text{ K}$ respectively per gram ($K_f = 5.1\text{ K kg mol}^{-1}$). What are the atomic masses of A and B?

A) $A = 25.59\text{ u}, B = 42.64\text{ u}$
B) $A = 42.64\text{ u}, B = 25.59\text{ u}$
C) $A = 110.87\text{ u}, B = 196.15\text{ u}$
D) $A = 50.00\text{ u}, B = 25.00\text{ u}$

Correct Answer: A) $A = 25.59\text{ u}, B = 42.64\text{ u}$

28. What is the concentration of a glucose solution exerting an osmotic pressure of $1.52\text{ bar}$ at $300\text{ K}$ ($R = 0.083\text{ bar L K}^{-1}\text{mol}^{-1}$)?

A) $0.061\text{ M}$
B) $0.152\text{ M}$
C) $0.300\text{ M}$
D) $0.083\text{ M}$

Correct Answer: A) $0.061\text{ M}$

29. Which type of intermolecular force is primary between n-hexane and n-octane?

A) Van der Waals forces
B) Hydrogen bonding
C) Ion-dipole interaction
D) Dipole-dipole forces

Correct Answer: A) Van der Waals forces

30. Arrange the following in increasing solubility in non-polar n-octane: $\text{KCl}$, $\text{CH}_3\text{OH}$, $\text{CH}_3\text{CN}$, $\text{Cyclohexane}$.

A) $\text{KCl} < \text{CH}_3\text{OH} < \text{CH}_3\text{CN} < \text{Cyclohexane}$
B) $\text{Cyclohexane} < \text{CH}_3\text{CN} < \text{CH}_3\text{OH} < \text{KCl}$
C) $\text{CH}_3\text{OH} < \text{KCl} < \text{Cyclohexane} < \text{CH}_3\text{CN}$
D) $\text{KCl} < \text{Cyclohexane} < \text{CH}_3\text{CN} < \text{CH}_3\text{OH}$

Correct Answer: A) $\text{KCl} < \text{CH}_3\text{OH} < \text{CH}_3\text{CN} < \text{Cyclohexane}$

31. Which of the following organic compounds is completely insoluble in water?

A) Formic acid
B) Ethylene glycol
C) Toluene
D) Phenol

Correct Answer: C) Toluene

32. Lake water contains $92\text{ g}$ of $\text{Na}^+$ ions per $\text{kg}$ of water. What is the molality of $\text{Na}^+$ ions in the lake?

A) $4\text{ m}$
B) $2\text{ m}$
C) $23\text{ m}$
D) $92\text{ m}$

Correct Answer: A) $4\text{ m}$

33. If the solubility product ($K_{sp}$) of $\text{CuS}$ is $6 \times 10^{-16}$, what is its maximum molarity in aqueous solution?

A) $2.45 \times 10^{-8}\text{ M}$
B) $6.00 \times 10^{-16}\text{ M}$
C) $3.00 \times 10^{-8}\text{ M}$
D) $1.20 \times 10^{-7}\text{ M}$

Correct Answer: A) $2.45 \times 10^{-8}\text{ M}$

34. What mass of benzoic acid ($\text{C}_6\text{H}_5\text{COOH}$) is needed to prepare $250\text{ mL}$ of a $0.15\text{ M}$ solution in methanol?

A) $4.575\text{ g}$
B) $122.0\text{ g}$
C) $0.0375\text{ g}$
D) $9.15\text{ g}$

Correct Answer: A) $4.575\text{ g}$

35. Which of the following acids produces the greatest depression in freezing point when equal amounts are added to water?

A) Acetic acid
B) Trichloroacetic acid
C) Trifluoroacetic acid
D) Monochloroacetic acid

Correct Answer: C) Trifluoroacetic acid

36. What is the depression in freezing point of water when $10\text{ g}$ of $\text{CH}_3\text{CH}_2\text{CHClCOOH}$ is added to $250\text{ g}$ of water ($K_a = 1.4 \times 10^{-3}$, $K_f = 1.86\text{ K kg mol}^{-1}$)?

A) $0.65\text{ K}$
B) $1.065\text{ K}$
C) $0.326\text{ K}$
D) $1.86\text{ K}$

Correct Answer: A) $0.65\text{ K}$

37. Dissolving $19.5\text{ g}$ of $\text{CH}_2\text{FCOOH}$ in $500\text{ g}$ of water lowers the freezing point by $1.0^\circ\text{C}$. What is its Van’t Hoff factor ($i$)?

A) $1.0753$
B) $0.0753$
C) $1.0000$
D) $2.0000$

Correct Answer: A) $1.0753$

38. Vapour pressure of pure water at $293\text{ K}$ is $17.535\text{ mm Hg}$. What is the vapour pressure of a solution containing $25\text{ g}$ glucose in $450\text{ g}$ water?

A) $17.44\text{ mm Hg}$
B) $17.535\text{ mm Hg}$
C) $0.097\text{ mm Hg}$
D) $15.00\text{ mm Hg}$

Correct Answer: A) $17.44\text{ mm Hg}$

39. What is the mole fraction solubility of methane in benzene at $298\text{ K}$ under $760\text{ mm Hg}$ if $K_H = 4.27 \times 10^5\text{ mm Hg}$?

A) $178 \times 10^{-5}$
B) $4.27 \times 10^{-5}$
C) $760 \times 10^{-5}$
D) $0.0178$

Correct Answer: A) $178 \times 10^{-5}$

40. Mixing acetone and chloroform shows negative deviation from Raoult’s law primarily due to:

A) Formation of hydrogen bonds between acetone and chloroform
B) Repulsion between solute and solvent molecules
C) Endothermic mixing ($\Delta H > 0$)
D) Increase in total vapour pressure

Correct Answer: A) Formation of hydrogen bonds between acetone and chloroform

41. What is the mole fraction of benzene in the vapour phase when $80\text{ g}$ of benzene is mixed with $100\text{ g}$ of toluene ($p^0_{\text{benzene}} = 50.71\text{ mm Hg}$, $p^0_{\text{toluene}} = 32.06\text{ mm Hg}$)?

A) $0.60$
B) $0.486$
C) $0.514$
D) $0.40$

Correct Answer: A) $0.60$

42. What amount of $\text{CaCl}_2$ ($i = 2.47$) is required in $2.5\text{ L}$ of water to produce an osmotic pressure of $0.75\text{ atm}$ at $27^\circ\text{C}$?

A) $3.42\text{ g}$
B) $111.0\text{ g}$
C) $1.50\text{ g}$
D) $5.25\text{ g}$

Correct Answer: A) $3.42\text{ g}$

43. Calculate the osmotic pressure of a solution prepared by dissolving $25\text{ mg}$ of $\text{K}_2\text{SO}_4$ in $2\text{ L}$ of water at $25^\circ\text{C}$, assuming complete dissociation ($i = 3$).

A) $5.27 \times 10^{-3}\text{ atm}$
B) $1.75 \times 10^{-3}\text{ atm}$
C) $5.27\text{ atm}$
D) $0.025\text{ atm}$

Correct Answer: A) $5.27 \times 10^{-3}\text{ atm}$

Class 12 Chemistry – Chapter 1: Solutions (All MCQs)

1. What is the mass percentage of benzene ($\text{C}_6\text{H}_6$) if $22\text{ g}$ of benzene is dissolved in $122\text{ g}$ of carbon tetrachloride ($\text{CCl}_4$)?

A) $84.72\%$
B) $15.28\%$
C) $18.03\%$
D) $22.00\%$

Correct Answer: B) $15.28\%$

2. What is the mole fraction of benzene in a solution containing $30\%$ by mass in carbon tetrachloride?

A) $0.458$
B) $0.542$
C) $0.384$
D) $0.154$

Correct Answer: A) $0.458$

3. What is the molarity of a solution prepared by dissolving $30\text{ g}$ of $\text{Co(NO}_3\text{)}_2 \cdot 6\text{H}_2\text{O}$ in $4.3\text{ L}$ of solution?

A) $0.050\text{ M}$
B) $0.023\text{ M}$
C) $0.103\text{ M}$
D) $0.030\text{ M}$

Correct Answer: B) $0.023\text{ M}$

4. What is the molarity of $30\text{ mL}$ of $0.5\text{ M }\text{H}_2\text{SO}_4$ diluted to $500\text{ mL}$?

A) $0.03\text{ M}$
B) $0.05\text{ M}$
C) $0.15\text{ M}$
D) $0.015\text{ M}$

Correct Answer: A) $0.03\text{ M}$

5. What mass of urea ($\text{NH}_2\text{CONH}_2$) is required in making $2.5\text{ kg}$ of a $0.25\text{ molal}$ aqueous solution?

A) $15\text{ g}$
B) $30\text{ g}$
C) $37\text{ g}$
D) $60\text{ g}$

Correct Answer: C) $37\text{ g}$

6. If the density of a $20\%$ (mass/mass) aqueous $\text{KI}$ solution is $1.202\text{ g mL}^{-1}$, what is its molality?

A) $1.45\text{ m}$
B) $1.51\text{ m}$
C) $0.0263\text{ m}$
D) $1.20\text{ m}$

Correct Answer: B) $1.51\text{ m}$

7. If the solubility of toxic gas $\text{H}_2\text{S}$ in water at STP is $0.195\text{ m}$, what is the Henry’s law constant ($K_H$)?

A) $282\text{ bar}$
B) $195\text{ bar}$
C) $0.0035\text{ bar}$
D) $55.56\text{ bar}$

Correct Answer: A) $282\text{ bar}$

8. Henry’s law constant for $\text{CO}_2$ in water is $1.67 \times 10^8\text{ Pa}$ at $298\text{ K}$. What quantity of $\text{CO}_2$ is present in $500\text{ mL}$ of soda water packed under $2.5\text{ atm }\text{CO}_2$ pressure?

A) $0.042\text{ g}$
B) $1.848\text{ g}$
C) $2.533\text{ g}$
D) $0.0015\text{ g}$

Correct Answer: B) $1.848\text{ g}$

9. Vapour pressure of pure liquids A and B are $450\text{ mm Hg}$ and $700\text{ mm Hg}$ respectively at $350\text{ K}$. If total vapour pressure is $600\text{ mm Hg}$, what is the mole fraction of liquid A in the liquid mixture?

A) $0.6$
B) $0.4$
C) $0.3$
D) $0.7$

Correct Answer: B) $0.4$

10. Vapour pressure of pure water at $298\text{ K}$ is $23.8\text{ mm Hg}$. When $50\text{ g}$ of urea is dissolved in $850\text{ g}$ of water, what is the relative lowering of vapour pressure?

A) $0.0173$
B) $23.4$
C) $0.83$
D) $0.050$

Correct Answer: A) $0.0173$

11. How much sucrose ($\text{C}_{12}\text{H}_{22}\text{O}_{11}$) must be added to $500\text{ g}$ of water to boil at $100^\circ\text{C}$ if it normally boils at $99.63^\circ\text{C}$ at $750\text{ mm Hg}$ ($K_b = 0.52\text{ K kg mol}^{-1}$)?

A) $342.00\text{ g}$
B) $121.67\text{ g}$
C) $0.37\text{ g}$
D) $500.00\text{ g}$

Correct Answer: B) $121.67\text{ g}$

12. What mass of ascorbic acid ($\text{C}_6\text{H}_8\text{O}_6$) is needed in $75\text{ g}$ of acetic acid to lower its melting point by $1.5^\circ\text{C}$ ($K_f = 3.9\text{ K kg mol}^{-1}$)?

A) $5.08\text{ g}$
B) $1.50\text{ g}$
C) $176.00\text{ g}$
D) $3.90\text{ g}$

Correct Answer: A) $5.08\text{ g}$

13. Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving $1.0\text{ g}$ of polymer (molar mass $185,000\text{ g mol}^{-1}$) in $450\text{ mL}$ of water at $37^\circ\text{C}$.

A) $31\text{ Pa}$
B) $310\text{ Pa}$
C) $185\text{ Pa}$
D) $8.314\text{ Pa}$

Correct Answer: A) $31\text{ Pa}$

14. Which of the following is an example of a solid solution in which the solute is a gas?

A) Solution of ethanol in water
B) Solution of copper in gold
C) Solution of hydrogen in palladium
D) Oxygen mixed with nitrogen gas

Correct Answer: C) Solution of hydrogen in palladium

15. What is the molarity of a concentrated nitric acid sample ($68\%$ $\text{HNO}_3$ by mass) with a density of $1.504\text{ g mL}^{-1}$?

A) $16.23\text{ M}$
B) $1.079\text{ M}$
C) $68.00\text{ M}$
D) $15.04\text{ M}$

Correct Answer: A) $16.23\text{ M}$

16. What volume of $0.1\text{ M }\text{HCl}$ is required to react completely with a $1\text{ g}$ equimolar mixture of $\text{Na}_2\text{CO}_3$ and $\text{NaHCO}_3$?

A) $159\text{ mL}$
B) $100\text{ mL}$
C) $106\text{ mL}$
D) $84\text{ mL}$

Correct Answer: A) $159\text{ mL}$

17. A solution is obtained by mixing $300\text{ g}$ of a $25\%$ solution and $400\text{ g}$ of a $40\%$ solution by mass. What is the mass percentage of solute in the resulting solution?

A) $33.57\%$
B) $66.43\%$
C) $35.00\%$
D) $23.50\%$

Correct Answer: A) $33.57\%$

18. What is the molality of an antifreeze solution prepared from $222.6\text{ g}$ of ethylene glycol ($\text{C}_2\text{H}_6\text{O}_2$) and $200\text{ g}$ of water?

A) $17.95\text{ m}$
B) $9.11\text{ m}$
C) $3.59\text{ m}$
D) $6.20\text{ m}$

Correct Answer: A) $17.95\text{ m}$

19. If a water sample is contaminated with chloroform ($\text{CHCl}_3$) at a level of $15\text{ ppm}$ by mass, what is its molality?

A) $1.26 \times 10^{-4}\text{ m}$
B) $1.5 \times 10^{-3}\text{ m}$
C) $1.195 \times 10^{-3}\text{ m}$
D) $1.26 \times 10^{-3}\text{ m}$

Correct Answer: A) $1.26 \times 10^{-4}\text{ m}$

20. What happens to the solubility of gases in liquids as temperature increases?

A) Increases because dissolution is endothermic
B) Decreases because dissolution is exothermic
C) Remains unchanged
D) Increases exponentially

Correct Answer: B) Decreases because dissolution is exothermic

21. Solutions exhibiting positive deviations from Raoult’s law show:

A) $\Delta_{\text{sol}} H < 0$
B) $\Delta_{\text{sol}} H > 0$ (Absorption of heat)
C) $\Delta_{\text{sol}} H = 0$
D) Decrease in total vapour pressure

Correct Answer: B) $\Delta_{\text{sol}} H > 0$ (Absorption of heat)

22. An aqueous solution of a $2\%$ non-volatile solute exerts a pressure of $1.004\text{ bar}$ at the normal boiling point of water ($1.013\text{ bar}$). What is the molar mass of the solute?

A) $41.35\text{ g mol}^{-1}$
B) $18.00\text{ g mol}^{-1}$
C) $98.00\text{ g mol}^{-1}$
D) $40.00\text{ g mol}^{-1}$

Correct Answer: A) $41.35\text{ g mol}^{-1}$

23. What is the vapour pressure of a $1\text{ molal}$ solution of a non-volatile solute in water at $300\text{ K}$ if pure water has a vapour pressure of $12.3\text{ kPa}$?

A) $12.08\text{ kPa}$
B) $12.30\text{ kPa}$
C) $0.217\text{ kPa}$
D) $11.50\text{ kPa}$

Correct Answer: A) $12.08\text{ kPa}$

24. What is the mass of a non-volatile solute (molar mass $= 40\text{ g mol}^{-1}$) required to be dissolved in $114\text{ g}$ of octane to reduce its vapour pressure to $80\%$?

A) $10\text{ g}$
B) $8\text{ g}$
C) $4\text{ g}$
D) $12\text{ g}$

Correct Answer: B) $8\text{ g}$

25. A solution containing $30\text{ g}$ of non-volatile solute in $90\text{ g}$ water has a vapour pressure of $2.8\text{ kPa}$. Adding $18\text{ g}$ of water changes it to $2.9\text{ kPa}$. What is the molar mass of the solute?

A) $23\text{ g mol}^{-1}$
B) $34\text{ g mol}^{-1}$
C) $40\text{ g mol}^{-1}$
D) $18\text{ g mol}^{-1}$

Correct Answer: A) $23\text{ g mol}^{-1}$

26. A $5\%$ solution of cane sugar (molar mass $342\text{ g mol}^{-1}$) freezes at $271\text{ K}$. What is the freezing point of a $5\%$ glucose solution (molar mass $180\text{ g mol}^{-1}$) in water? (Freezing point of pure water $= 273.15\text{ K}$)

A) $269.06\text{ K}$
B) $271.00\text{ K}$
C) $273.15\text{ K}$
D) $265.50\text{ K}$

Correct Answer: A) $269.06\text{ K}$

27. Compounds $\text{AB}_2$ and $\text{AB}_4$ dissolved in $20\text{ g}$ benzene lower the freezing point by $2.3\text{ K}$ and $1.3\text{ K}$ respectively per gram ($K_f = 5.1\text{ K kg mol}^{-1}$). What are the atomic masses of A and B?

A) $A = 25.59\text{ u}, B = 42.64\text{ u}$
B) $A = 42.64\text{ u}, B = 25.59\text{ u}$
C) $A = 110.87\text{ u}, B = 196.15\text{ u}$
D) $A = 50.00\text{ u}, B = 25.00\text{ u}$

Correct Answer: A) $A = 25.59\text{ u}, B = 42.64\text{ u}$

28. What is the concentration of a glucose solution exerting an osmotic pressure of $1.52\text{ bar}$ at $300\text{ K}$ ($R = 0.083\text{ bar L K}^{-1}\text{mol}^{-1}$)?

A) $0.061\text{ M}$
B) $0.152\text{ M}$
C) $0.300\text{ M}$
D) $0.083\text{ M}$

Correct Answer: A) $0.061\text{ M}$

29. Which type of intermolecular force is primary between n-hexane and n-octane?

A) Van der Waals forces
B) Hydrogen bonding
C) Ion-dipole interaction
D) Dipole-dipole forces

Correct Answer: A) Van der Waals forces

30. Arrange the following in increasing solubility in non-polar n-octane: $\text{KCl}$, $\text{CH}_3\text{OH}$, $\text{CH}_3\text{CN}$, $\text{Cyclohexane}$.

A) $\text{KCl} < \text{CH}_3\text{OH} < \text{CH}_3\text{CN} < \text{Cyclohexane}$
B) $\text{Cyclohexane} < \text{CH}_3\text{CN} < \text{CH}_3\text{OH} < \text{KCl}$
C) $\text{CH}_3\text{OH} < \text{KCl} < \text{Cyclohexane} < \text{CH}_3\text{CN}$
D) $\text{KCl} < \text{Cyclohexane} < \text{CH}_3\text{CN} < \text{CH}_3\text{OH}$

Correct Answer: A) $\text{KCl} < \text{CH}_3\text{OH} < \text{CH}_3\text{CN} < \text{Cyclohexane}$

31. Which of the following organic compounds is completely insoluble in water?

A) Formic acid
B) Ethylene glycol
C) Toluene
D) Phenol

Correct Answer: C) Toluene

32. Lake water contains $92\text{ g}$ of $\text{Na}^+$ ions per $\text{kg}$ of water. What is the molality of $\text{Na}^+$ ions in the lake?

A) $4\text{ m}$
B) $2\text{ m}$
C) $23\text{ m}$
D) $92\text{ m}$

Correct Answer: A) $4\text{ m}$

33. If the solubility product ($K_{sp}$) of $\text{CuS}$ is $6 \times 10^{-16}$, what is its maximum molarity in aqueous solution?

A) $2.45 \times 10^{-8}\text{ M}$
B) $6.00 \times 10^{-16}\text{ M}$
C) $3.00 \times 10^{-8}\text{ M}$
D) $1.20 \times 10^{-7}\text{ M}$

Correct Answer: A) $2.45 \times 10^{-8}\text{ M}$

34. What mass of benzoic acid ($\text{C}_6\text{H}_5\text{COOH}$) is needed to prepare $250\text{ mL}$ of a $0.15\text{ M}$ solution in methanol?

A) $4.575\text{ g}$
B) $122.0\text{ g}$
C) $0.0375\text{ g}$
D) $9.15\text{ g}$

Correct Answer: A) $4.575\text{ g}$

35. Which of the following acids produces the greatest depression in freezing point when equal amounts are added to water?

A) Acetic acid
B) Trichloroacetic acid
C) Trifluoroacetic acid
D) Monochloroacetic acid

Correct Answer: C) Trifluoroacetic acid

36. What is the depression in freezing point of water when $10\text{ g}$ of $\text{CH}_3\text{CH}_2\text{CHClCOOH}$ is added to $250\text{ g}$ of water ($K_a = 1.4 \times 10^{-3}$, $K_f = 1.86\text{ K kg mol}^{-1}$)?

A) $0.65\text{ K}$
B) $1.065\text{ K}$
C) $0.326\text{ K}$
D) $1.86\text{ K}$

Correct Answer: A) $0.65\text{ K}$

37. Dissolving $19.5\text{ g}$ of $\text{CH}_2\text{FCOOH}$ in $500\text{ g}$ of water lowers the freezing point by $1.0^\circ\text{C}$. What is its Van’t Hoff factor ($i$)?

A) $1.0753$
B) $0.0753$
C) $1.0000$
D) $2.0000$

Correct Answer: A) $1.0753$

38. Vapour pressure of pure water at $293\text{ K}$ is $17.535\text{ mm Hg}$. What is the vapour pressure of a solution containing $25\text{ g}$ glucose in $450\text{ g}$ water?

A) $17.44\text{ mm Hg}$
B) $17.535\text{ mm Hg}$
C) $0.097\text{ mm Hg}$
D) $15.00\text{ mm Hg}$

Correct Answer: A) $17.44\text{ mm Hg}$

39. What is the mole fraction solubility of methane in benzene at $298\text{ K}$ under $760\text{ mm Hg}$ if $K_H = 4.27 \times 10^5\text{ mm Hg}$?

A) $178 \times 10^{-5}$
B) $4.27 \times 10^{-5}$
C) $760 \times 10^{-5}$
D) $0.0178$

Correct Answer: A) $178 \times 10^{-5}$

40. Mixing acetone and chloroform shows negative deviation from Raoult’s law primarily due to:

A) Formation of hydrogen bonds between acetone and chloroform
B) Repulsion between solute and solvent molecules
C) Endothermic mixing ($\Delta H > 0$)
D) Increase in total vapour pressure

Correct Answer: A) Formation of hydrogen bonds between acetone and chloroform

41. What is the mole fraction of benzene in the vapour phase when $80\text{ g}$ of benzene is mixed with $100\text{ g}$ of toluene ($p^0_{\text{benzene}} = 50.71\text{ mm Hg}$, $p^0_{\text{toluene}} = 32.06\text{ mm Hg}$)?

A) $0.60$
B) $0.486$
C) $0.514$
D) $0.40$

Correct Answer: A) $0.60$

42. What amount of $\text{CaCl}_2$ ($i = 2.47$) is required in $2.5\text{ L}$ of water to produce an osmotic pressure of $0.75\text{ atm}$ at $27^\circ\text{C}$?

A) $3.42\text{ g}$
B) $111.0\text{ g}$
C) $1.50\text{ g}$
D) $5.25\text{ g}$

Correct Answer: A) $3.42\text{ g}$

43. Calculate the osmotic pressure of a solution prepared by dissolving $25\text{ mg}$ of $\text{K}_2\text{SO}_4$ in $2\text{ L}$ of water at $25^\circ\text{C}$, assuming complete dissociation ($i = 3$).

A) $5.27 \times 10^{-3}\text{ atm}$
B) $1.75 \times 10^{-3}\text{ atm}$
C) $5.27\text{ atm}$
D) $0.025\text{ atm}$

Correct Answer: A) $5.27 \times 10^{-3}\text{ atm}$

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Class 12 Chemistry – Chapter 1: Solutions (All MCQs)

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