Adsorption and Colloids — Class 11 MCQs with Answers
Class 11 CBSE Chemistry · Chapter 306
40 practice questions · 20 Easy · 20 Medium · Updated
Practise the most important Class 11 CBSE Chemistry questions from Chapter 306, "Adsorption and Colloids". You get 4 timed quizzes made from 40 NCERT-based MCQs, with answers and explanations. The questions are split into 20 Easy and 20 Medium. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG apart.
To score well in "Adsorption and Colloids", focus on reactions, key concepts and careful numericals. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Adsorption and Colloids, then move to Medium to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 11 Chemistry mastery score. 6 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Adsorption and Colloids (Class 11 Chemistry)
This chapter is about what happens at surfaces and about the state of matter that sits between a true solution and a suspension. It begins by separating adsorption, a surface phenomenon, from absorption, a bulk phenomenon, and distinguishes weak physisorption held by van der Waals forces from strong, specific chemisorption held by chemical bonds, summarising the pressure dependence in the Freundlich adsorption isotherm x/m = k p^(1/n). Surface chemistry then explains catalysis, both homogeneous and heterogeneous, through the adsorption theory of active centres. The second half studies colloids: how they are classified as lyophilic or lyophobic and as multimolecular, macromolecular or associated, how micelles form above the critical micelle concentration, how sols are prepared and purified by dialysis, electrodialysis and ultrafiltration, and how their characteristic behaviour — the Tyndall effect, Brownian motion, electrophoresis and coagulation governed by the Hardy-Schulze rule — arises from particle size and surface charge.
- Adsorption
- The accumulation of a substance at the surface of a solid or liquid, so that its concentration at the surface is higher than in the interior. It occurs because atoms at a surface have unbalanced attractive forces, and it is always exothermic since it lowers the surface energy of the adsorbent.
- Absorption and sorption
- Absorption is a bulk phenomenon in which a substance is taken up uniformly throughout another, as water is by a sponge or anhydrous CaCl₂. When adsorption and absorption happen together and cannot easily be told apart, as with a dye on cotton, the combined process is called sorption.
- Adsorbate and adsorbent
- The adsorbate is the substance that gets held on the surface, and the adsorbent is the solid that provides that surface. Good adsorbents such as activated charcoal, silica gel and alumina all have very large surface areas per gram, which is why finely divided or porous forms adsorb best.
- Physisorption
- Physical adsorption in which the adsorbate is held by weak van der Waals forces. Its enthalpy is only about 20 to 40 kJ mol⁻¹, it needs no activation energy, it is not specific to any particular gas, it can form multiple layers, and it is easily reversed by heating or by reducing the pressure.
Adsorption and Colloids — important questions & MCQs with answers (Class 11 Chemistry)
6 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 34 are timed and scored when you sign in.
- Q1Easy
The accumulation of a substance at the surface of a solid rather than in its bulk is called
A.absorptionB.diffusionC.adsorption✓ CorrectD.condensationAnswer: C. adsorption
Explanation: Adsorption is strictly a surface phenomenon: the concentration of the substance is higher at the surface than in the interior of the solid.
- Q2Easy
Physical adsorption of a gas on a solid is caused by
A.formation of covalent bondsB.weak van der Waals forces✓ CorrectC.formation of ionic bondsD.transfer of electrons to the adsorbentAnswer: B. weak van der Waals forces
Explanation: In physisorption the adsorbate is held only by weak van der Waals attraction, which is why the process is readily reversible and has a small enthalpy change.
- Q3Easy
A substance that alters the rate of a chemical reaction but is itself left chemically unchanged at the end is called a
A.catalyst✓ CorrectB.adsorbateC.peptising agentD.dispersion mediumAnswer: A. catalyst
Explanation: A catalyst changes the rate by providing an alternative path of lower activation energy and is recovered unchanged in mass and chemical composition.
- Q4Medium
Which of the following changes will increase the extent of adsorption of a gas on charcoal?
A.Powdering the charcoal to increase its surface area✓ CorrectB.Raising the temperature of the systemC.Lowering the pressure of the gasD.Choosing a gas with a very low critical temperatureAnswer: A. Powdering the charcoal to increase its surface area
Explanation: Adsorption is a surface phenomenon, so finely divided or activated charcoal, with its very large surface area per gram, adsorbs far more gas.
- Q5Medium
Which statement correctly distinguishes chemisorption from physisorption?
A.Chemisorption is highly specific and forms only a unimolecular layer✓ CorrectB.Chemisorption has an enthalpy of only about 20 kJ mol⁻¹C.Chemisorption is easily reversed by lowering the pressureD.Chemisorption requires no activation energy at allAnswer: A. Chemisorption is highly specific and forms only a unimolecular layer
Explanation: Because real chemical bonds form, chemisorption occurs only between particular adsorbate-adsorbent pairs and stops once every surface site is occupied, giving a single layer.
- Q6Medium
Which of the following is an example of homogeneous catalysis?
A.Synthesis of ammonia over finely divided ironB.Oxidation of SO₂ to SO₃ over solid V₂O₅C.Hydrolysis of an ester catalysed by dilute H₂SO₄ in aqueous solution✓ CorrectD.Hydrogenation of vegetable oil using nickelAnswer: C. Hydrolysis of an ester catalysed by dilute H₂SO₄ in aqueous solution
Explanation: In the ester hydrolysis both the reactants and the acid catalyst are in the same liquid phase; the other three involve a solid catalyst acting on fluid reactants.
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Start this chapter free →Adsorption and Colloids — FAQs
What are the key concepts in Class 11 Chemistry Adsorption and Colloids?+
This chapter is about what happens at surfaces and about the state of matter that sits between a true solution and a suspension. It begins by separating adsorption, a surface phenomenon, from absorption, a bulk phenomenon, and distinguishes weak physisorption held by van der Waals forces from strong, specific chemisorption held by chemical bonds, summarising the pressure dependence in the Freundlich adsorption isotherm x/m = k p^(1/n). Surface chemistry then explains catalysis, both homogeneous and heterogeneous, through the adsorption theory of active centres. The second half studies colloids: how they are classified as lyophilic or lyophobic and as multimolecular, macromolecular or associated, how micelles form above the critical micelle concentration, how sols are prepared and purified by dialysis, electrodialysis and ultrafiltration, and how their characteristic behaviour — the Tyndall effect, Brownian motion, electrophoresis and coagulation governed by the Hardy-Schulze rule — arises from particle size and surface charge. Key ideas include Adsorption, Absorption and sorption, Adsorbate and adsorbent, Physisorption.
What does Class 11 Chemistry Chapter 306 (Adsorption and Colloids) cover on XamBaaz?+
It has 40 NCERT-based MCQs on "Adsorption and Colloids": 20 Easy and 20 Medium. Together they make 4 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG.
Are these "Adsorption and Colloids" questions free to practise?+
Yes. Sign in with Google to practise "Adsorption and Colloids" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Adsorption and Colloids" for the exam?+
Start with the Easy quiz to check your basics, then try Medium to practise applying them. There are 4 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Adsorption and Colloids" MCQs available with answers?+
Yes. 6 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Adsorption and Colloids" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as JEE Main, JEE Advanced and NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Adsorption and Colloids (Class 11 Chemistry)?+
The questions that matter most test Adsorption, Absorption and sorption, Adsorbate and adsorbent, Physisorption. This page shows 6 solved important MCQs with answers and explanations; all 40 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Adsorption and Colloids?+
Yes — Class 11 Chemistry Adsorption and Colloids has timed online quizzes at Easy and Medium levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.