Take timed practice tests on Surface Chemistry for JEE Main and JEE Advanced with session-wise drills, score review, and explanation-led revision.
Six 20-question timed sessions plus a 60-question chapter module. Each item is original and reframed for copyright safety.
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1. The process by which a substance accumulates on the surface of another is called:
Explanation: Adsorption: accumulation of a substance (adsorbate) on the surface of another (adsorbent). Absorption: bulk process where substance penetrates throughout (sponge soaking water). 'Adsorption on surface, absorption in bulk.'
2. Chemisorption involves:
Explanation: Physisorption: weak van der Waals forces, reversible, multi-layer, low ΔH (~20-40 kJ/mol), occurs at low T. Chemisorption: chemical bonds formed, stronger (ΔH ~80-240 kJ/mol), mono-layer, specific, higher activation energy, increases then decreases with T.
3. The Freundlich adsorption isotherm: x/m = k p^(1/n). At high pressure, x/m is:
Explanation: Freundlich isotherm: x/m = kp^(1/n). At low p: x/m ∝ p^(1/n). At high p: 1/n → 1, x/m ∝ p. At very high p: adsorption becomes independent of p (surface saturation).
4. The size range of colloidal particles is:
Explanation: Particle size classification: True solutions ( 1000 nm, do not pass filter paper).
5. The Tyndall effect is observed in colloids because:
Explanation: Tyndall effect: when a beam of light passes through a colloid, the path of the beam becomes visible due to scattering by the colloidal particles. True solutions do not show this (particles too small). Used to distinguish sol from true solution.
6. Coagulation of a negatively charged colloid is best done by:
Explanation: Hardy-Schulze rule: for coagulating a negatively charged colloid, cations are needed. Higher the valence of the cation, greater the coagulating power. Al³⁺ > Ca²⁺ > Na⁺ (in terms of coagulating power). Alum (Al₂(SO₄)₃) is used to purify water (coagulates negatively charged clay/silt colloids).
7. Enzyme catalysis shows specificity because:
Explanation: Enzyme specificity: the active site is complementary in shape and charge to the specific substrate molecule. Only the correct substrate can fit and react. This gives enzymes absolute (one substrate) or group (class of substrates) specificity.
8. Emulsions are colloidal systems of:
Explanation: Emulsion: liquid in liquid colloid (e.g., milk, mayonnaise). Emulsifiers (surfactants) stabilise emulsions. O/W emulsion: oil in water (milk). W/O emulsion: water in oil (butter).
9. Peptisation is the process of:
Explanation: Peptisation: a freshly prepared precipitate is converted into a colloid by adding a small amount of electrolyte (peptising agent) that is adsorbed on the particles, giving them charge → repulsion stabilises the colloid. E.g., AgCl precipitate + AgNO₃ → AgCl sol.