Aqueous solutions MCQs class 12 chemistry form one of the most important and frequently tested areas in the Class 12 Chemistry syllabus. An aqueous solution is a solution in which water acts as the solvent, and most real-life chemical processes—whether biological, industrial, or environmental—occur in aqueous media. Because of this, aqueous solutions MCQs class 12 chemistry are designed to test both conceptual clarity and numerical problem-solving skills.

In board examinations and competitive exams like NEET, JEE, and CUET, aqueous solutions MCQs class 12 chemistry often focus on concentration terms such as molarity, molality, normality, mole fraction, and parts per million.  Aspirants are expected to convert between these units accurately, identify temperature-dependent quantities, and apply formulas correctly under time pressure. Mastery of these topics ensures confidence while solving aqueous solutions MCQs class 12 chemistry.

Another major area covered under aqueous solutions MCQs class 12 chemistry is colligative properties. These include lowering of vapour pressure, elevation of boiling point, depression of freezing point, and osmotic pressure. Questions frequently test the application of formulas involving van’t Hoff factor, especially for electrolytes that undergo dissociation or association in aqueous solutions. Practicing aqueous solutions MCQs class 12 chemistry helps aspirants avoid common mistakes related to ion count and degree of ionization.

Electrolytes and non-electrolytes play a critical role in aqueous solutions MCQs class 12 chemistry. Strong electrolytes, weak electrolytes, and non-electrolytes behave differently in water, and MCQs often compare their effects on osmotic pressure or freezing point depression. Understanding how ionic strength changes solution behavior is essential for solving aqueous solutions MCQs class 12 chemistry accurately.

The concept of osmotic pressure is especially important in aqueous solutions MCQs class 12 chemistry, as it is widely used for determining molar masses of macromolecules like proteins and polymers. Questions may involve isotonic, hypotonic, and hypertonic solutions, making it crucial to clearly understand these terms. Regular practice of aqueous solutions MCQs class 12 chemistry strengthens logical reasoning in such applications.

Temperature dependence is another recurring theme in aqueous solutions MCQs class 12 chemistry. Molarity changes with temperature, whereas molality and mole fraction remain constant. MCQs often test this subtle difference, and aspirants who practice aqueous solutions MCQs class 12 chemistry regularly can easily identify the correct choice without lengthy calculations.

Real exam questions under aqueous solutions MCQs class 12 chemistry also involve Henry’s law and Raoult’s law for aqueous solutions containing gases or volatile components. These questions assess the ability to relate vapour pressure with mole fraction and partial pressure, which is essential for scoring well in competitive exams.

One effective strategy to master aqueous solutions MCQs class 12 chemistry is to categorize questions into theory-based MCQs, numerical MCQs, and assertion-reason type MCQs. This structured practice improves speed and accuracy.

Aqueous Solutions MCQs Class 12 Chemistry with Solved Answers

1) A solution containing 4 g of polyvinyl chloride polymer in one litre of dioxane was found to have an osmotic pressure of 4.1 x 10⁻⁴ atm at 27°C. The approximate molecular weight of the polymer is
A) 1500
B) 10000
C) 2.4 x 10⁵
D) 2 x 10⁴
Answer: C

2) Two solutions of KNO₃ and CH₃COOH are prepared separately. Molarity of both is 0.1 M and osmotic pressures are P₁ and P₂ respectively. The correct relationship between the osmotic pressures is
A) P₁ > P₂
B) P₁ = P₂
C) P₁ < P₂
D) P1P1+P2=P2P1+P2\frac {P_1}{P_1 + P_2} = \frac {P_2}{P_1 + P_2}P1​+P2​P1​​=P1​+P2​P2​​
Answer: A

3) The osmotic pressure is expressed in units of
A) MeV
B) calories
C) cm/sec
D) atmosphere
Answer: D

4) Osmotic pressure of 0.4% urea solution is 1.64 atm and that of 3.42% cane sugar is 2.46 atm. When the above two solutions are mixed, the osmotic pressure of the resulting solution is
A) 0.82 atm
B) 2.46 atm
C) 1.64 atm
D) 4.1 atm
Answer: B

5) Two solutions with equal osmotic pressure are
A) normal solutions
B) isotonic solutions
C) hypotonic solutions
D) hypertonic solutions
Answer: B

6) Four solutions A, B, C, D has glucose 0.5 M, NaCl 0.1 M, BaCl₂ 0.5 M and MgCl₂ 0.1 M, then which of the following will have highest osmotic pressure?
A) Glucose
B) BaCl₂
C) MgCl₂
D) NaCl
Answer: B

7) The pair of components which cannot exist together in solution is
A) NaHCO₃ and NaOH
B) NaHCO₃ and H₂O
C) NaHCO₃ and Na₂CO₃
D) Na₂CO₃ and NaOH
Answer: A

8) Identify the correct order of solubility of Na₂S, CuS, and ZnS in aqueous medium
A) CuS > ZnS > Na₂S
B) ZnS > Na₂S > CuS
C) Na₂S > CuS > ZnS
D) Na₂S > ZnS > CuS
Answer: D

9) In which solution/solvent the solubility of AgCl is minimum?
A) 0.01 M NaCl
B) 0.01 M CaCl₂
C) Pure water
D) 0.01 M AgNO₃
Answer: B

10) The water having more dissolved O₂ is
A) Boiling water
B) Water at 80°C
C) Polluted water
D) Water at 4°C
Answer: D

11) Henry’s constant (in kbar) for four gases α, β, γ, and δ in water at 298 K is given. This table implies that
A) α has the highest solubility in water at a given pressure
B) Solubility of γ at 308 K is lower than at 298 K
C) The pressure of a 55.5 molal solution of γ is 1 bar
D) The pressure of a 55.5 molal solution of δ is 250 bar
Answer: D

12) At 35°C, the vapour pressure of CS₂ is 512 mm Hg and that of acetone is 344 mm Hg. A solution has total vapour pressure 600 mm Hg. The false statement is
A) Raoult’s law is not obeyed by this system
B) CS₂ and acetone are less attracted to each other than to themselves
C) A mixture of 100 mL CS₂ and 100 mL acetone has a volume < 200 mL
D) Heat must be absorbed to produce the solution at 35°C
Answer: C

13) Which statement regarding Henry’s law is not correct?
A) Different gases have different KHK_HKH​ at same temperature
B) Higher KHK_HKH​ → higher solubility at given pressure
C) KHK_HKH​ increases with temperature and depends on gas nature
D) Partial pressure ∝ mole fraction in solution
Answer: B

14) For gases w, x, y and z in water at 298 K, the correct plot is
A) Option 1
B) Option 2
C) Option 3
D) Option 4
Answer: A

15) AgCl is soluble in NH₄OH. The solubility is due to formation of
A) AgOH
B) Ag₂O
C) [Ag(NH₃)₂]⁺
D) NH₄Cl
Answer: C

16) Out of BeF₂, MgF₂, CaF₂, SrF₂ which has maximum solubility
A) BeF₂
B) MgF₂
C) SrF₂
D) CaF₂
Answer: A

17) Which compound is least soluble?
A) Na₂S
B) MgS
C) MgCl₂
D) NaCl
Answer: B

18) Which is most soluble in water?
A) CsClO₄
B) NaClO₄
C) KClO₄
D) LiClO₄
Answer: D

19) Correct conditions for real solutions showing negative deviation from Raoult’s law
A) ΔHmix<0; ΔVmix>0\Delta H_{mix} < 0;\ \Delta V_{mix} > 0ΔHmix​<0; ΔVmix​>0
B) ΔHmix>0; ΔVmix>0\Delta H_{mix} > 0;\ \Delta V_{mix} > 0ΔHmix​>0; ΔVmix​>0
C) ΔHmix>0; ΔVmix<0\Delta H_{mix} > 0;\ \Delta V_{mix} < 0ΔHmix​>0; ΔVmix​<0
D) ΔHmix<0; ΔVmix<0\Delta H_{mix} < 0;\ \Delta V_{mix} < 0ΔHmix​<0; ΔVmix​<0
Answer: D

20) You have 500 mL each of 2N HCl and 5N HCl. Maximum volume of 3M HCl you can prepare is
A) 250 mL
B) 500 mL
C) 750 mL
D) 1000 mL
Answer: C

21) When BaCl₂ is added to an aqueous salt solution, a white ppt is obtained. The anion among CO₃²⁻, SO₃²⁻, SO₄²⁻ can be
A) CO₃²⁻ only
B) SO₃²⁻ only
C) SO₄²⁻ only
D) Any of them
Answer: D

22) PbCl₂ is insoluble in cold water. Addition of HCl increases its solubility due to
A) Formation of soluble complex anions like [PbCl₃]⁻
B) Oxidation of Pb(II) to Pb(IV)
C) Formation of [Pb(H₂O)₆]²⁺
D) Formation of polymeric lead complex
Answer: A

23) At 20°C, solubility of N₂ in water is 0.015 g/L at 580 torr. Solubility at 800 torr is
A) 0.207 g/L
B) 0.0207 g/L
C) 0.414 g/L
D) 0.081 g/L
Answer: B

24) At 80°C, PA0=520P_A^0=520PA0​=520 mm Hg and PB0=1000P_B^0=1000PB0​=1000 mm Hg. If mixture boils at 80°C and 1 atm, amount of A is
A) 50 mol percent
B) 32 mol percent
C) 44 mol percent
D) 54 mol percent
Answer: A

25) Which alcohol has highest solubility in water?
A) Secondary butyl alcohol
B) Tertiary butyl alcohol
C) Ethylene glycol
D) Glycerol
Answer: D

26) 50 g of saturated KCl solution at 30°C is evaporated to dryness and 13.2 g KCl obtained. Solubility of KCl in water at 30°C is
A) 35.87 g
B) 25.62 g
C) 28.77 g
D) 27.81 g
Answer: A

27) 100 mL of 0.1 M acetic acid is neutralized using NaOH. Volume of ethane obtained at STP after electrolysis is
A) 56 mL
B) 224 mL
C) 560 mL
D) 112 mL
Answer: D

28) Assuming fully decomposed, volume of CO₂ at STP on heating 9.85 g of BaCO₃ is
A) 1.12 L
B) 0.84 L
C) 2.24 L
D) 4.06 L
Answer: A

29) Vapour pressure decreases by 10 mm Hg; mole fraction of solute = 0.2. If vapour pressure decreases by 20 mm Hg now, mole fraction of solute is
A) 0.2
B) 0.4
C) 0.6
D) 0.8
Answer: C

30) Which salt gives an acidic solution in water?
A) CH₃COONa
B) NH₄Cl
C) NaCl
D) CH₃COONH₄
Answer: B