JEE Chemistry Surface Chemistry MCQs Set 05

Download JEE MCQs for JEE Chemistry: Surface Chemistry

Access targeted multiple-choice questions for Surface Chemistry designed to align with the latest JEE academic syllabus for JEE Chemistry. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.

Chapter-wise Objective Questions: Surface Chemistry

Access the complete set of multiple-choice questions for Surface Chemistry below. This focused format allows students to isolate specific topics for thorough review and uninterrupted practice alongside official JEE textbooks.

Multiple Choice Questions

Question 1: The Hardy-Schulze rule states that
(a) Non-electrolytes have better coagulating action on colloids than electrolytes
(b) Sols are coagulated by effective ions whose charge is opposite to that of the sol, and ions of higher charge are much more effective than ions of lower charge
(c) The charge of the ions has no effect on the coagulation of a sol
(d) Sols are coagulated only by those ions whose charge is similar to that of the sol
Show Answer & Explanation

Answer: (b) Sols are coagulated by effective ions whose charge is opposite to that of the sol, and ions of higher charge are much more effective than ions of lower charge

Explanation:
1. Coagulation is brought about by the ion carrying a charge opposite to that of the sol.
2. The higher the charge, the greater the effect.

Teacher's Note:
1. Opposite charge neutralises the sol.

Question 2: An example of a micelle is
(a) As2O3 sol
(b) Ruby glass
(c) Na2CO3 solution
(d) Concentrated sodium stearate solution
Show Answer & Explanation

Answer: (d) Concentrated sodium stearate solution

Explanation:
1. Sodium stearate above its critical micelle concentration forms micelles.
2. The others are not associated colloids.

Teacher's Note:
1. Soap is the classic micelle example.

Question 3: To coagulate a gelatin sol, which of the following is most effective?
(a) NaCl
(b) Na3PO4
(c) AlCl3
(d) Alcohol
Show Answer & Explanation

Answer: (d) Alcohol

Explanation:
1. Gelatin is a lyophilic sol stabilised mostly by solvation.
2. Alcohol removes the solvation layer, so it coagulates the sol.

Teacher's Note:
1. Electrolytes are weak for lyophilic sols.

Question 4: Which of the following has the minimum flocculation value for a negatively charged sol?
(a) \( \ce{Pb^{2+}} \)
(b) \( \ce{Pb^{4+}} \)
(c) \( \ce{Sr^{2+}} \)
(d) \( \ce{Na+} \)
Show Answer & Explanation

Answer: (b) \( \ce{Pb^{4+}} \)

Explanation:
1. The higher the charge on the cation, the smaller the flocculation value.
2. Pb4+ has the highest charge.

Teacher's Note:
1. Greater valency means lower flocculation value.

Question 5: The gold numbers of A, B, C and D are 0.04, 0.002, 10 and 25 respectively. The protective powers of A, B, C and D are in the order
(a) A > B > C > D
(b) B > A > C > D
(c) D > C > B > A
(d) C > A > B > D
Show Answer & Explanation

Answer: (b) B > A > C > D

Explanation:
1. Protective power is inversely proportional to the gold number.
2. So the order is B (0.002) > A (0.04) > C (10) > D (25).

Teacher's Note:
1. Smaller gold number means better protection.

Question 6: On addition of 1 mL of 10% NaCl solution to 10 mL of gold sol in presence of 0.025 g of starch, coagulation is just prevented. The gold number of starch is
(a) 25
(b) 2.5
(c) 0.25
(d) 0.025
Show Answer & Explanation

Answer: (a) 25

Explanation:
1. The gold number is the mass in milligrams of protective colloid that just prevents coagulation of 10 mL of gold sol.
2. 0.025 g is 25 mg.

Teacher's Note:
1. Convert grams to milligrams.

Question 7: Gold number is a measure of
(a) The amount of gold present in the colloidal solution
(b) The amount of gold required to break the colloid
(c) The amount of gold required to protect the colloid
(d) None of the above
Show Answer & Explanation

Answer: (d) None of the above

Explanation:
1. The gold number is the mass of the protective colloid, not of gold, that protects 10 mL of gold sol.
2. So none of the statements is correct.

Teacher's Note:
1. Gold number measures protective power.

Question 8: Opal (a mineral with liquid inclusions) is a
(a) Gel (liquid dispersed in solid phase)
(b) Solid sol (solid dispersed in solid phase)
(c) Sol (solid dispersed in liquid)
(d) Foam (gas dispersed in liquid)
Show Answer & Explanation

Answer: (a) Gel (liquid dispersed in solid phase)

Explanation:
1. Opal consists of a liquid dispersed in a solid medium, which is a gel.
2. It is not a solid sol or a foam.

Teacher's Note:
1. Gel: liquid in solid.

Question 9: Some of the following are true solutions: I Air, II Sea water, III Glucose solution, IV Gem stone, V Pearl, VI Blood. The true solutions are
(a) I, II, III
(b) II, III, IV, V
(c) I, IV, V, VI
(d) II, IV, VI
Show Answer & Explanation

Answer: (a) I, II, III

Explanation:
1. Air (gases), sea water and glucose solution are homogeneous true solutions.
2. Pearl is a gel-type system and blood is a colloid.

Teacher's Note:
1. True solution has particles below 1 nm.

Question 10: In multimolecular colloidal sols, atoms or molecules are held together by
(a) Hydrogen bonding
(b) van der Waals forces
(c) Ionic bonding
(d) Polar covalent bonding
Show Answer & Explanation

Answer: (b) van der Waals forces

Explanation:
1. Multimolecular colloids, such as sulphur sol, are aggregates held by weak van der Waals forces.
2. Macromolecular colloids have covalent bonds.

Teacher's Note:
1. Weak forces hold the aggregates.

Question 11: The Tyndall effect is NOT observed in
(a) Suspension
(b) Starch sol
(c) Gold sol
(d) NaCl solution
Show Answer & Explanation

Answer: (d) NaCl solution

Explanation:
1. A true solution has particles too small to scatter light.
2. Colloids and suspensions scatter light.

Teacher's Note:
1. Tyndall effect needs large particles.

Question 12: Which is a kinetic phenomenon?
(a) Brownian motion
(b) Tyndall effect
(c) Both (1) and (2)
(d) None of these
Show Answer & Explanation

Answer: (a) Brownian motion

Explanation:
1. Brownian motion arises from the random motion of molecules.
2. Tyndall effect is an optical property.

Teacher's Note:
1. Kinetic property: Brownian motion, diffusion.

Question 13: Which pair is correctly matched?
(a) [Fe(OH)3]Fe3+ : Cl-
(b) [As2S3] : As3+
(c) [SnO2] : SnO3 2- in acidic medium
(d) [AgI] : I- in excess of AgNO3
Show Answer & Explanation

Answer: (a) [Fe(OH)3]Fe3+ : Cl-

Explanation:
1. The positively charged ferric hydroxide sol has Fe3+ adsorbed, with Cl- as counter ion.
2. The other pairs are not correct.

Teacher's Note:
1. Sol particle: adsorbed ion, counter ion.

Question 14: The gold number of haemoglobin is 0.03. The amount of haemoglobin required so that 100 mL of gold sol is not coagulated by 10 mL of 10% NaCl solution is
(a) 0.03 mg
(b) 30 mg
(c) 0.30 mg
(d) 3 mg
Show Answer & Explanation

Answer: (c) 0.30 mg

Explanation:
1. Gold number 0.03 mg protects 10 mL of sol.
2. For 100 mL the amount is 10 times larger, 0.30 mg.

Teacher's Note:
1. Scale the volume.

Question 15: Which is NOT a correct matching of emulsions?
(a) Milk : O/W
(b) Cold cream : W/O
(c) Butter : O/W
(d) Vanishing cream : O/W
Show Answer & Explanation

Answer: (c) Butter : O/W

Explanation:
1. Butter is a water-in-oil (W/O) emulsion.
2. Milk and vanishing cream are O/W, and cold cream is W/O.

Teacher's Note:
1. Butter is W/O.

Question 16: Which of the following statements is correct?
(a) A catalyst accelerates the rate of a chemical reaction
(b) A catalyst can retard the rate of a chemical reaction
(c) A catalyst can control the speed of a reaction in both directions differently
(d) A catalyst does not alter the speed of a reaction
Show Answer & Explanation

Answer: (a) A catalyst accelerates the rate of a chemical reaction

Explanation:
1. A catalyst increases the rate by providing a path of lower activation energy.
2. A substance that retards a reaction is an inhibitor.

Teacher's Note:
1. Catalyst speeds up reactions.

Question 17: Which one of the following is NOT an example of homogeneous catalysis?
(a) Formation of SO3 in the lead chamber process
(b) Formation of SO3 in the contact process
(c) Hydrolysis of an ester in presence of acid
(d) Decomposition of KClO3 in presence of MnO2
Show Answer & Explanation

Answer: (d) Decomposition of KClO3 in presence of MnO2

Explanation:
1. In KClO3 decomposition solid MnO2 is the catalyst, so reactant and catalyst are in different phases.
2. The others have the same phase throughout (or are the lead chamber examples).

Teacher's Note:
1. Heterogeneous: different phase.

Question 18: The decomposition of hydrogen peroxide can be slowed down by adding a small amount of acetanilide. The latter acts as
(a) An inhibitor
(b) A promoter
(c) A moderator
(d) A poison
Show Answer & Explanation

Answer: (a) An inhibitor

Explanation:
1. Acetanilide retards the reaction and is a negative catalyst or inhibitor.
2. A promoter increases catalyst activity and a poison deactivates the catalyst.

Teacher's Note:
1. Inhibitor slows reactions by itself.

Question 19: The efficiency of a catalyst depends on its
(a) Molecular weight
(b) Number of free valencies
(c) Physical state
(d) Amount of reactant used
Show Answer & Explanation

Answer: (b) Number of free valencies

Explanation:
1. Free valencies at the surface adsorb the reactants, so efficiency rises with the number of free valencies.
2. This explains why transition metals are good catalysts.

Teacher's Note:
1. Adsorption theory of catalysis.

Question 20: Which of the following types of metals make the most efficient catalysts?
(a) Transition metals
(b) Alkali metals
(c) Alkaline earth metals
(d) Radioactive metals
Show Answer & Explanation

Answer: (a) Transition metals

Explanation:
1. Transition metals have unpaired d-electrons and vacant d-orbitals and can bind reactants.
2. They are variable valency.

Teacher's Note:
1. d-block metals are good catalysts.

Question 21: In the reaction \( KMnO_4+H_2SO_4+H_2C_2O_4\to \) products, the Mn\(^{2+}\) ions act as
(a) A positive catalyst
(b) A negative catalyst
(c) An autocatalyst
(d) An enzyme catalyst
Show Answer & Explanation

Answer: (c) An autocatalyst

Explanation:
1. Mn2+ is a product of the reaction and speeds it up.
2. A product that catalyses its own formation is an autocatalyst.

Teacher's Note:
1. Reaction starts slowly then accelerates.

Question 22: In Haber's process of synthesis of NH3
(a) Mo acts as a catalyst and Fe as a promoter
(b) Fe acts as a catalyst and Mo as a promoter
(c) Fe acts as an inhibitor and Mo as a catalyst
(d) Fe acts as a promoter and Mo as an autocatalyst
Show Answer & Explanation

Answer: (b) Fe acts as a catalyst and Mo as a promoter

Explanation:
1. Finely divided iron is the catalyst and molybdenum is the promoter.
2. The promoter increases the activity of the catalyst.

Teacher's Note:
1. Fe + Mo for ammonia.

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Surface Chemistry Objective Questions & Solutions for JEE Chemistry

JEE Chemistry Surface Chemistry Objective Test Questions

Test your conceptual understanding of Surface Chemistry with these targeted multiple-choice questions. Designed in alignment with the latest JEE curriculum for JEE Chemistry, these problem sets build accuracy and prepare students for objective exams.

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FAQs

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