Solutions NEET PYQs (2005–2026) with Solutions

10 solved Solutions PYQs

Real NEET and AIPMT questions from this chapter, newest first. Try each one, then open the answer and the step-by-step explanation.

1. Question 1 (NEET 2026)

   NEET 2026EasyIdeal solutions and intermolecular interactions

   Assertion A: For an ideal solution formed by mixing liquids P and Q, $\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$ Reason R: No interactions occur between P and Q In the light of the above statements, choose the most appropriate answer from the options given below.

   1. AOption A: Both A and R are correct and R is the correct explanation of A
   2. BOption B: Both A and R are correct but R is NOT the correct explanation of A
   3. COption C: A is correct but R is not correct
   4. DOption D: A is not correct but R is correct

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   Correct answer: (C) A is correct but R is not correct

   Explanation

   Assertion A is correct. An ideal solution obeys Raoult's law over the whole composition range, and for it $\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$: no heat is absorbed or released on mixing, and the volume of the solution equals the sum of the volumes of the components. Reason R is wrong. P and Q do interact. In an ideal solution, the P–Q interactions are nearly equal to the P–P and Q–Q interactions. So mixing does not change the total energy or volume. So the answer is option (C).

2. Question 2 (NEET 2026)

   NEET 2026MediumMolality, molarity, Henry’s law and mole fraction

   Identify the correct statements: (A) The molality of 2.5 g of ethanoic acid (Molar mass: 60 g mol⁻¹) in 75 g of benzene solution is 0.556 m. (B) The molarity of a solution containing 5 g of NaOH (molar mass: 40 g mol⁻¹) in 450 mL of solution is 0.278 M at 298 K. (C) Aquatic species are more comfortable in cold water. (D) The solubility of gas increases with decrease in pressure. (E) For a binary mixture of A and B, the number of moles of A and B are nₐ and nᵦ respectively. The mole fraction of B will be: Xᵦ = nₐ / (nₐ + nᵦ) Choose the correct answer from the options given below :

   1. AOption A: A, B and C only
   2. BOption B: A and B only
   3. COption C: A and C only
   4. DOption D: A, D and E only

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   Correct answer: (A) A, B and C only

   Explanation

   A: molality=(2.5/60)×1000/75=0.556 m (true). B: molarity=(5/40)/(450/1000)=0.278 M (true). C: gases are more soluble in cold water (true). D is false because gas solubility increases with pressure. E is false since mole fraction of B=xB=nB/(nA+nB). Hence option (A) is correct.

3. Question 3 (NEET 2026)

   NEET 2026EasyIdeal and non-ideal solutions, Raoult's law deviations

   Consider the following statements about the solutions formed by mixing two liquids. A. An ideal solution thus formed obeys Raoult's law throughout the composition range. B. Mixture of chloroform and acetone shows negative deviation from Raoult's law. C. Mixture of aniline and phenol shows positive deviation from Raoult's law.

   1. AOption A: A and B only
   2. BOption B: B and C only
   3. COption C: A only
   4. DOption D: A and C only

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   Correct answer: (A) A and B only

   Explanation

   A is correct: an ideal solution obeys Raoult's law over the entire range of concentration. B is correct: chloroform forms a hydrogen bond with acetone ($\mathrm{Cl_3C{-}H \cdots O{=}C(CH_3)_2}$). The A–B attraction is stronger than A–A and B–B, so the vapour pressure falls and the mixture shows negative deviation. C is incorrect: phenol and aniline form intermolecular hydrogen bonds ($\mathrm{O{-}H \cdots N}$), which are stronger than those in the pure liquids. So this mixture shows negative, not positive, deviation. So A and B only: option (A).

4. Question 4 (NEET 2026)

   NEET 2026EasyIdeal & Non-Ideal Solutions

   Mixture of chloroform and acetone forms a solution with negative deviation from Raoult’s law due to:

   1. AOption A: Increase in escaping tendency of molecules of each component
   2. BOption B: Formation of hydrogen bonding between acetone and chloroform
   3. COption C: Stronger intermolecular forces between chloroform molecules than those between chloroform and acetone molecules
   4. DOption D: Repulsive forces

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   Correct answer: (B) Formation of hydrogen bonding between acetone and chloroform

   Explanation

   Acetone and chloroform form intermolecular hydrogen bonding between the oxygen atom of acetone and hydrogen of chloroform. This strengthens attractive forces, lowers vapour pressure and causes negative deviation from Raoult’s law. Hence option (B) is correct.

5. Question 5 (NEET 2025)

   NEET 2025EasyTypes of Solutions

   Match List-I with List-II Choose the correct answer from the options given below :

   1. AOption A: A-II, B-IV, C-I, D-III
   2. BOption B: A-II, B-I, C-IV, D-III
   3. COption C: A-III, B-I, C-IV, D-II
   4. DOption D: A-III, B-II, C-I, D-IV

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   Correct answer: (B) A-II, B-I, C-IV, D-III

   Explanation

   Humidity is an example of liquid in gas solution. Alloys are solid in solid solutions. Amalgams are liquid in solid solutions because mercury is dissolved in a metal. Smoke is an example of solid in gas colloidal system. Hence, the correct matching is A-II, B-I, C-IV, D-III, which corresponds to option (B).

6. Question 6 (NEET 2025)

   NEET 2025EasyColligative Properties

   Which of the following aqueous solution will exhibit highest boiling point?

   1. AOption A: 0.01 M Urea
   2. BOption B: 0.01 M KNO₃
   3. COption C: 0.01 M Na₂SO₄
   4. DOption D: 0.015 M C₆H₁₂O₆

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   Correct answer: (C) 0.01 M Na₂SO₄

   Explanation

   Elevation in boiling point depends on i × C, where i is van’t Hoff factor and C is concentration. For urea: i × C = 1 × 0.01 = 0.01 For KNO₃: i × C = 2 × 0.01 = 0.02 For Na₂SO₄: i × C = 3 × 0.01 = 0.03 For glucose: i × C = 1 × 0.015 = 0.015 Na₂SO₄ gives the highest effective particle concentration, hence highest boiling point.

7. Question 7 (NEET 2025)

   NEET 2025MediumIdeal & Non-Ideal Solutions

   5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is true regarding the described solution?

   1. AOption A: The solution shows positive deviation.
   2. BOption B: The solution shows negative deviation.
   3. COption C: The solution is ideal.
   4. DOption D: The solution has volume greater than the sum of individual volumes.

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   Correct answer: (B) The solution shows negative deviation.

   Explanation

   According to Raoult's law, the ideal vapour pressure is: Pideal = (5/15 × 63) + (10/15 × 78) = 21 + 52 = 73 torr Observed vapour pressure is 70 torr, which is less than the ideal value. Hence the solution shows negative deviation from Raoult's law.

8. Question 8 (NEET 2024)

   NEET 2024EasySolubility & Vapour Pressure

   The Henry’s law constant (K$_H$) values of three gases A, B, C in water are 145, 2×10⁻⁵ and 35 kbar respectively. The solubility of these gases in water follows:

   1. AOption A: A > C > B
   2. BOption B: A > B > C
   3. COption C: B > A > C
   4. DOption D: B > C > A

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   Correct answer: (D) B > C > A

   Explanation

   According to Henry’s law, solubility is inversely proportional to Henry’s constant. Given: $$K_H(B)=2\times10^{-5} < K_H(C)=35 < K_H(A)=145$$ Therefore solubility order is: $$B > C > A$$ Hence, option (D) is correct.

9. Question 9 (NEET 2022)

   NEET 2022EasyConcentration Terms

   In one molal solution that contains 0.5 mole of a solute, there is:

   1. AOption A: 1000 g of solvent
   2. BOption B: 500 mL of solvent
   3. COption C: 500 g of solvent
   4. DOption D: 100 mL of solvent

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   Correct answer: (C) 500 g of solvent

   Explanation

   Molality: m = moles of solute / kg of solvent 1 = 0.5 / kg solvent Thus solvent = 0.5 kg = 500 g Hence option (C) is correct.

10. Question 10 (NEET 2020)

    NEET 2020MediumPartial Pressure of Gases

    A mixture of N$_2$ and Ar gases in a cylinder contains 7 g of N$_2$ and 8 g of Ar. If the total pressure of the mixture of the gases in the cylinder is 27 bar, the partial pressure of N$_2$ is: [Use atomic masses (in g mol⁻¹): N = 14, Ar = 40]

    1. AOption A: 9 bar
    2. BOption B: 12 bar
    3. COption C: 15 bar
    4. DOption D: 18 bar

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    Correct answer: (C) 15 bar

    Explanation

    Moles of N2 = 7/28 = 0.25 mol Moles of Ar = 8/40 = 0.20 mol Total moles = 0.25 + 0.20 = 0.45 mol Mole fraction of N2: XN2 = 0.25/0.45 = 5/9 Partial pressure of N2: PN2 = XN2 × Ptotal = (5/9) × 27 = 15 bar Hence, the correct answer is 15 bar.