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NEET Surface Chemistry PYQs & Practice Questions

10 free NEET Chemistry questions on Surface Chemistry, starting with previous year questions (2016–2023). Tap “Show answer” to check each one. No login needed.

Topics: Adsorption · Freundlich Adsorption Isotherm · Catalysis · Colloids · Colloidal Properties · Emulsions · Coagulation · Preparation of Colloids · Enzyme Catalysis · Emulsions and Colloid Stability · Processes Occurring at a Phase Interface · Thermodynamic Condition at Adsorption Equilibrium

  1. Q1NEET 2023Heterogeneous Catalysis

    Which one is an example of heterogeneous catalysis?

    • A. Hydrolysis of sugar catalysed by H+ ions.
    • B. Decomposition of ozone in presence of nitrogen monoxide.
    • C. Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron.
    • D. Oxidation of Sulphur dioxide into Sulphur trioxide in the presence of oxides of nitrogen.
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    Answer: B — Decomposition of ozone in presence of nitrogen monoxide.

    In heterogeneous catalysis, the catalyst is in a different phase from the reactants. The Haber process (N2(g) + 3H2(g) <-> 2NH3(g)) uses finely divided iron, a solid catalyst, with gaseous reactants, making it heterogeneous catalysis. The other options involve catalysts in the same phase as the reactants (homogeneous catalysis).

  2. Q2NEET 2023Types of Colloids

    Pumice stone is an example of:

    • A. gel
    • B. solid sol
    • C. foam
    • D. sol
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    Answer: A — gel

    Pumice stone is a solid colloidal system where gas is dispersed in a solid dispersion medium, making it an example of a solid sol.

  3. Q3NEET 2022Coagulation of Colloids

    Given below are statements: Statement I: In the coagulation of negative sol, the flocculating power of the three given ions is in the order: Al3+ > Ba2+ > Na+ Statement II: In the coagulation of a positive sol, the flocculating power of the three given salts is in the order: NaCl > Na2SO4 > Na3PO4 In the light of the above statements, choose the most appropriate answer from the options given below:

    • A. Both Statement I and Statement II are incorrect.
    • B. Statement I is correct but Statement II is incorrect.
    • C. Statement I is incorrect but Statement II is correct.
    • D. Both Statement I and Statement II are correct.
    Show answer

    Answer: A — Both Statement I and Statement II are incorrect.

    Statement I is correct: for negative sol coagulation, higher charge cations have greater flocculating power, so Al3+ > Ba2+ > Na+ (Hardy-Schulze rule). Statement II is incorrect: for positive sol coagulation, the anion with higher charge has greater flocculating power, so the correct order should be Na3PO4 > Na2SO4 > NaCl, not the reverse as stated.

  4. Q4NEET 2022Hardy-Schulze Rule - Flocculating Power

    Given below are two statements: Statement I: In the coagulation of a negative sol, the flocculating power of the three given ions is in the order Al3+ > Ba2+ > Na+. Statement II: In the coagulation of a positive sol, the flocculating power of the three given salts is in the order NaCl > Na2SO4 > Na3PO4. In the light of the above statements, choose the most appropriate answer from the options given below:

    • A. Both Statement I and Statement II are correct.
    • B. Both Statement I and Statement II are incorrect.
    • C. Statement I is correct but Statement II is incorrect.
    • D. Statement I is incorrect but Statement II is correct.
    Show answer

    Answer: B — Both Statement I and Statement II are incorrect.

    Statement I is correct per the Hardy-Schulze rule: higher charge cations have greater flocculating power for negative sols, so Al3+ > Ba2+ > Na+. Statement II is incorrect because for a positive sol, the anion determines flocculating power, and higher charge anions are more effective, so the order should be Na3PO4 > Na2SO4 > NaCl (opposite of what's stated).

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  5. Q5NEET 2021Identifying a colloid that shows the Tyndall effect

    The right option for the statement 'Tyndall effect is exhibited by', is:

    • A. NaCl solution
    • B. Glucose solution
    • C. Starch solution
    • D. Urea solution
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    Answer: B — Glucose solution

    Starch solution is a colloidal system, and colloids scatter light, showing the Tyndall effect (true solutions like NaCl, glucose, urea do not).

  6. Q6NEET 2020Zeta potential and colloid stability

    Measuring Zeta potential is useful in determining which property of colloidal solution?

    • A. Viscosity
    • B. Solubility
    • C. Stability of the colloidal particles
    • D. Size of the colloidal particles
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    Answer: B — Solubility

    Zeta potential is a measure of the electrostatic charge/potential at the slipping plane of colloidal particles, which determines the degree of repulsion between particles and hence the stability of the colloidal dispersion.

  7. Q7NEET 2020Types of detergents (cationic)

    Which of the following is a cationic detergent?

    • A. Sodium lauryl sulphate
    • B. Sodium stearate
    • C. Cetyltrimethyl ammonium bromide
    • D. Sodium dodecylbenzene sulphonate
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    Answer: B — Sodium stearate

    Cetyltrimethyl ammonium bromide has a positively charged quaternary ammonium group as its hydrophilic head, making it a cationic detergent, unlike the other options which are anionic (sulphate/sulphonate/carboxylate) surfactants.

  8. Q8NEET 2018Coagulation of colloids (Hardy-Schulze rule)

    On which of the following properties does the coagulating power of an ion depend?

    • A. The magnitude of the charge on the ion alone
    • B. The sign of charge on the ion alone
    • C. Both magnitude and sign of the charge on the ion
    • D. Size of the ion alone
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    Answer: B — The sign of charge on the ion alone

    According to the Hardy-Schulze rule, the coagulating power of an ion depends on both the sign of its charge (must be opposite to that of the colloidal particle) and the magnitude of that charge (greater charge gives greater coagulating power).

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  9. Q9NEET 2016Coagulation of Colloids (Hardy-Schulze Rule)

    The coagulation values in millimoles per litre of the electrolytes used for the coagulation of As2S3 are given below: I. (NaCl) = 52, II. (BaCl2) = 0.69, III. (MgSO4) = 0.22. The correct order of their coagulating power is:

    • A. III > I > II
    • B. I > II > III
    • C. II > I > III
    • D. III > II > I
    Show answer

    Answer: C — II > I > III

    As2S3 is a negative sol. Coagulating power ∝ charge on cation, and ∝ 1/(coagulation value). Lower coagulation value means higher coagulating power: III(0.22) > II(0.69) > I(52)

  10. Q10Adsorption

    Which is NOT a property of lyophilic colloids?

    • A. High viscosity
    • B. High solvation
    • C. Reversible
    • D. Lower stability than lyophobic
    Show answer

    Answer: C — Reversible

    Lyophilic (solvent-loving) colloids: high viscosity, good solvation, reversible, MORE stable than lyophobic (require stabilizers). Lyophobic = solvent-hating, less stable, irreversible.

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