The no. of positively and negatively charged sols respectively in the following areTiO , blood, CdS, Cu, Ag, Clay, SiO , Fe O
1
5, 3
2
3, 5
3
6, 2
4
4, 4
Official Solution
Correct Option:
(4)
Colloidal sols can be positively or negatively charged depending on the preferential adsorption of ions from the dispersion medium or due to the nature of the dispersed phase itself. Common examples of charged sols:
Positively charged sols:
\begin{itemize} \item Metal hydroxides/hydrated oxides: e.g., Fe(OH) , Al(OH) , Cr(OH) . Hydrated Fe O (like Fe O H O) is generally positive. \item Metal oxides: e.g., TiO . \item Basic dyes: e.g., methylene blue. \item Proteins in acidic medium (pHNegatively charged sols:
\begin{itemize} \item Metal sulfides: e.g., As S , CdS, Sb S . \item Metals: e.g., sols of gold (Au), silver (Ag), copper (Cu), platinum (Pt). \item Acidic dyes: e.g., eosin, congo red. \item Starch, gum, gelatin, clay, silicic acid (SiO as hydrated silica or silicic acid sol). \item Proteins in basic medium (pH>isoelectric point).
\end{itemize} Let's classify the given sols: % Option
(A) TiO (Titanium dioxide): Metal oxide sol, generally positively charged. (+1)
% Option
(B) Blood: Haemoglobin in blood is a protein sol, generally positively charged. (+1)
% Option
(C) CdS (Cadmium sulfide): Metal sulfide sol, generally negatively charged. (-1)
% Option
(D) Cu (Copper): Metal sol, generally negatively charged. (-1)
% Option
(E) Ag (Silver): Metal sol, generally negatively charged. (-1)
% Option
(F) Clay: Generally negatively charged (due to silicate structures and ion exchange). (-1)
% Option
(G) SiO (Silicon dioxide/Silicic acid): Generally negatively charged. (-1)
% Option
(H) Fe O (Ferric oxide): Hydrated ferric oxide sol (Fe O H O) is generally positively charged. (+1) (Note: Sometimes, depending on preparation method, Fe O can be negative if it adsorbs OH ions in excess, but commonly it's positive by adsorbing Fe or H ). Given Fe O without specific context, it often implies the hydrated positive sol.
\end{itemize}
Correcting some common classifications:
\begin{itemize}
% Option
(I) TiO : Positively charged.
% Option
(J) Blood (Haemoglobin): Positively charged.
% Option
(K) CdS: Negatively charged.
% Option
(L) Cu: Negatively charged.
% Option
(M) Ag: Negatively charged.
% Option
(N) Clay: Negatively charged.
% Option
(O) SiO : Negatively charged.
% Option
(P) Fe O H O (hydrated ferric oxide): Positively charged.
\end{itemize}
Based on these common classifications:
Positively charged sols: TiO , Blood, Fe O . (Count = 3)
Negatively charged sols: CdS, Cu, Ag, Clay, SiO . (Count = 5)
This gives a ratio of 3:5. This matches option (b). However, the marked correct answer is (d) 4, 4. This implies a different classification for one of the sols.
If Fe O is considered positively charged, and TiO positively charged, and Blood positively charged, this is 3.
If SiO were positive, then positive count = 4. (TiO , Blood, Fe O , SiO ).
Then negative sols: CdS, Cu, Ag, Clay. (Count = 4).
This would give 4, 4.
The charge on SiO sols can depend on pH. Silicic acid is H SiO . At neutral or basic pH, it deprotonates to form SiO based structures which are negative. At very low pH, it might be positive by adsorbing H . However, generally, silica sol is considered negative.
Let's assume the question intends for SiO to be positive to match the answer (d). This is not standard. Alternative possibility: Fe O sol could be negatively charged if prepared in excess OH .
If we need 4 positive, 4 negative:
Positive: TiO , Blood. (+2 so far)
Negative: CdS, Cu, Ag, Clay. (-4 so far)
Remaining: SiO , Fe O .
If SiO is negative (standard), then total negative = 5.
If Fe O is positive (standard), then total positive = 3. Let's consult standard lists:
Positively charged: Metal hydroxides [Fe(OH) , Al(OH) ], metal oxides (TiO ), basic dyes (methylene blue), proteins in acidic medium, haemoglobin.
Negatively charged: Metal sulfides (As S , CdS), metal sols (Au, Ag, Cu), acidic dyes (eosin), starch, gums, gelatin, clay, silicic acid. Using this standard list:
TiO : Positive
Blood (haemoglobin): Positive
CdS: Negative
Cu: Negative
Ag: Negative
Clay: Negative
SiO (silicic acid): Negative
Fe O (hydrated ferric oxide sol, Fe(OH) type): Positive Positively charged = TiO , Blood, Fe O . (Count = 3)
Negatively charged = CdS, Cu, Ag, Clay, SiO . (Count = 5)
This gives (3, 5), which is option (b). Given the provided solution is (d) 4,4, there is a discrepancy. To get (4,4), one typically positive sol must be negative, or one typically negative sol must be positive.
For example, if Blood was negative (e.g., proteins in basic medium, but "blood" itself is usually taken as positive due to haemoglobin at physiological pH), OR if Fe O was negative.
And one negative sol (e.g., SiO ) was positive. If SiO is taken as positive (e.g. in highly acidic conditions adsorbing H ):
Positive: TiO , Blood, Fe O , SiO (Count = 4)
Negative: CdS, Cu, Ag, Clay (Count = 4)
This combination (SiO as positive) would yield the answer (4,4). This is a less common assumption for SiO without pH context but might be intended to fit the answer.
Let's proceed with this assumption to match the answer.
(Note: Standard classification leads to 3 Pos, 5 Neg. To get 4,4, SiO is assumed positive here.)
02
PYQ 2022
medium
chemistryID: ap-eapce
The molality and molarity of a solution of glucose in water which is labeled as 10% (w/w) are respectively (density of solution = 1.2 g/mL)
1
0.57 m, 0.517 M
2
0.67 m, 0.61 M
3
0.611 m, 0.67 M
4
0.517 m, 0.57 M
Official Solution
Correct Option:
(3)
Assume 100 g of solution:
- Glucose = 10 g
- Water = 90 g = 0.090 kg Molality:
Molarity:
03
PYQ 2022
medium
chemistryID: ap-eapce
The macromolecular colloids of the following are:
1
I, II
2
II, III
3
III, IV
4
I, IV
Official Solution
Correct Option:
(4)
Macromolecular colloids are those where large-sized molecules form a colloidal dispersion.
I. Starch solution and IV. Synthetic rubber are macromolecular colloids.
II. Sulphur sol is a multimolecular colloid.
III. Synthetic detergent forms micelles, i.e., associated colloids.
04
PYQ 2022
medium
chemistryID: ap-eapce
The colloidal solution used to treat stomach disorders is:
1
Silver sol
2
Antimony sol
3
Milk of magnesia
4
Gold sol
Official Solution
Correct Option:
(3)
Milk of magnesia is a colloidal solution of magnesium hydroxide , used as an antacid to neutralize excess hydrochloric acid in the stomach and treat acidity. It is a solid in liquid type colloid.
05
PYQ 2022
medium
chemistryID: ap-eapce
Freundlich adsorption isotherm fails at which of the following condition?
1
High temperature
2
Low temperature
3
High Pressure
4
Low pressure
Official Solution
Correct Option:
(3)
The Freundlich adsorption isotherm is an empirical equation that describes the adsorption of a gas onto a solid surface. It is given by:
where:
is the mass of the gas adsorbed
is the mass of the adsorbent
is the pressure of the gas
and are constants that depend on the nature of the adsorbent and the gas, and on the temperature ( ). The Freundlich isotherm has limitations:
\begin{itemize} \item It is an empirical equation and does not have a strong theoretical basis. \item It is valid over a limited range of pressures. \item At high pressures: The amount of gas adsorbed ( ) approaches a saturation value, meaning it becomes independent of pressure (i.e., becomes constant). However, the Freundlich equation ( ) predicts that will continue to increase with pressure (though at a decreasing rate since ). Thus, the Freundlich isotherm fails to accurately describe adsorption at high pressures where saturation occurs. The Langmuir isotherm provides a better description at high pressures and predicts monolayer adsorption leading to saturation. \item At very low pressures: The Freundlich isotherm often fits well. Here , which means adsorption is nearly linear with pressure (if ). \item Temperature dependence: The constants and change with temperature. The isotherm itself is usually applied at a constant temperature. High temperature generally leads to less adsorption (desorption is favored), and low temperature favors adsorption. The failure is primarily related to pressure ranges rather than temperature absolutes, although the constants change with temperature.
\end{itemize} The primary condition under which the Freundlich isotherm fails is at high pressures, where it does not predict the observed saturation of adsorption.
Option (c) High Pressure is the condition where it fails.
06
PYQ 2022
medium
chemistryID: ap-eapce
The diameter range of colloidal particles is approximately:
1
1 to 1000 nm
2
1000 to 2000 nm
3
2000 to 3000 nm
4
3000 to 4000 nm
Official Solution
Correct Option:
(1)
Colloidal particles typically have diameters ranging from 1 to 1000 nanometers. Below 1 nm → true solution; above 1000 nm → suspension.
07
PYQ 2022
medium
chemistryID: ap-eapce
The sol formed in the following unbalanced equation is:
1
2
3
As
4
S
Official Solution
Correct Option:
(2)
Arsenic trioxide reacts with hydrogen sulfide to form arsenic trisulfide , which is a colloidal sol:
Arsenic trisulfide appears as a yellow precipitate and forms a sol in water.
08
PYQ 2023
medium
chemistryID: ap-eapce
Consider the following statements for a gold sol:
I) It is macromolecular colloid
II) It is a lyophobic sol
III) It is a negatively charged sol
IV) It is a multimolecular colloid
V) It is an associated colloid
The correct statements are:
1
I, II, III only
2
II, III, IV only
3
III, IV, V only
4
I, IV, V only
Official Solution
Correct Option:
(2)
Step 1: Analyze the nature of a gold sol.
A gold sol is typically prepared by the reduction of gold salts (like AuCl ) in water. The gold atoms formed aggregate to form colloidal particles. Step 2: Evaluate each statement.
\begin{itemize} \item I) It is macromolecular colloid: Macromolecular colloids are formed by large molecules (macromolecules) in a suitable solvent. Examples include starch, proteins, and polymers. Gold sol particles are aggregates of many gold atoms, not single large molecules. So, this is incorrect. \item II) It is a lyophobic sol: Lyophobic colloids (solvent-hating) are formed by substances that do not readily form colloidal solutions. They are thermodynamically unstable and require stabilizing agents. Metal sols like gold sol are lyophobic. So, this is correct. \item III) It is a negatively charged sol: Gold sols prepared by reduction methods often have a negative charge due to the adsorption of anions (like citrate ions if sodium citrate is used as a reducing agent) on the surface of the gold particles. So, this is correct. \item IV) It is a multimolecular colloid: Multimolecular colloids are formed by the aggregation of a large number of small atoms or molecules. Gold sol, consisting of aggregates of many gold atoms, fits this description. So, this is correct. \item V) It is an associated colloid: Associated colloids (micelles) are formed by the aggregation of lyophilic colloids at high concentrations. Examples include soaps and detergents. Gold sol formation is different from micelle formation. So, this is incorrect.
\end{itemize} Step 3: Identify the correct statements.
The correct statements are II, III, and IV. Final Answer:
09
PYQ 2023
medium
chemistryID: ap-eapce
For the reaction A + B → C, the following data were obtained: The order of reaction with respect to A and B are respectively
1
1, 2
2
2, 1
3
1.5, 1.5
4
0, 3
Official Solution
Correct Option:
(1)
Let the rate law be: Rate = For order w.r.t B (y):
Compare Expt 1 & 2 (constant [A]):
For order w.r.t A (x):
Compare Expt 2 & 3 (constant [B]):
Thus, orders are 1 (A) and 2 (B). Answer: (1).
10
PYQ 2023
medium
chemistryID: ap-eapce
Match the following
List – I
(Dispersed Phase – Dispersion medium)
A) Solid – Liquid
B) Liquid – Liquid
C) Solid – Gas
D) Liquid – Solid
List – II
(Type of colloid)
I) Gel
II) Aerosol
III) Sol
IV) Emulsion
The correct answer is
1
A - II, B - III, C - I, D - IV
2
A - III, B - IV, C - II, D - I
3
A - III, B - IV, C - I, D - II
4
A - I, B - III, C - IV, D - II
Official Solution
Correct Option:
(2)
To match the type of colloid with the phase combination, we need to know the characteristics of each colloid:
Sol (A-III): A sol is a colloidal system in which the dispersed phase is a solid and the dispersion medium is a liquid. Example: Paint, ink, etc.
Emulsion (B-IV): An emulsion is formed when both dispersed and dispersion phases are liquids. These are immiscible liquids forming a stable colloidal system, such as milk (fat in water).
Aerosol (C-II): Aerosols are formed when solids or liquids are dispersed in a gas. For this option, solid in gas means smoke or dust in air.
Gel (D-I): A gel is a colloidal system in which the dispersed phase is liquid and the dispersion medium is solid. Common examples include jelly or butter.
Thus, correct matching is:
11
PYQ 2023
medium
chemistryID: ap-eapce
Some statements about Leclanche ll are: Anode is zinc metal Cathode is graphite rod surrounded by powdered {MnO2} and carbon Electrolyte is a moist paste of ZnO and KOH Oxidation product is ZnO
1
only statements I and II are correct.
2
only statements I is correct.
3
only statements II is correct.
4
None of them are correct.
Official Solution
Correct Option:
(1)
The Leclanché cell is a type of primary battery (non-rechargeable) that operates via redox reactions between zinc and manganese dioxide.
Statement I: Anode is zinc metal — Correct. Zinc metal acts as the anode and undergoes oxidation, releasing electrons:
Statement II: Cathode is graphite rod surrounded by powdered and carbon — Correct. The cathode consists of a graphite rod which acts as an inert conductor, embedded in a mixture of manganese dioxide and carbon powder. is reduced:
Statement III: Electrolyte is a moist paste of and — Incorrect. This is not true for a Leclanché cell. The electrolyte in a Leclanché cell is actually a moist paste of ammonium chloride ( ) and zinc chloride ( ), not .
Statement IV: Oxidation product is — Incorrect. In the Leclanché cell, the oxidation product is , typically forming , not .
Hence, only statements I and II are correct.
12
PYQ 2023
medium
chemistryID: ap-eapce
The most effective coagulating agent for antimony sulphide sol is:
1
2
3
4
Official Solution
Correct Option:
(3)
The coagulating agent that is most effective in coagulating an antimony sulphide sol is . This is because alum (potassium aluminium sulphate) is commonly used as a coagulating agent for sols, including antimony sulphide sols, by neutralizing the charge on the colloidal particles, which leads to their aggregation. Thus, the correct coagulating agent for antimony sulphide sol is .
13
PYQ 2023
medium
chemistryID: ap-eapce
The greater the valence of the flocculating ion added, the greater is its power to cause precipitation of a colloid. This rule is:
1
Hund’s rule
2
Pauling rule
3
Henry’s rule
4
Hardy–Schulze rule
Official Solution
Correct Option:
(4)
The Hardy–Schulze rule states that the effectiveness of an ion in precipitating a colloid increases with its valence. For instance, Al\textsuperscript{3+} is more effective than Ba\textsuperscript{2+} or Na\textsuperscript{+} in precipitating negatively charged colloids.
14
PYQ 2023
medium
chemistryID: ap-eapce
Identify the correct statement from the following:
1
Unbranched hydrocarbon detergents are non-biodegradable
2
Cetyltrimethyl ammonium bromide is used in hair conditioners
3
Liquid dish washing detergents are anionic type
4
Synthetic detergents cannot be used in hard water
Official Solution
Correct Option:
(2)
Step 1: Evaluate each statement.
\begin{itemize} \item (1) Unbranched hydrocarbon detergents are non-biodegradable: Branched hydrocarbon detergents are less biodegradable due to the difficulty of microbial enzymes to break down the branched chains. Unbranched (linear) hydrocarbon detergents are generally biodegradable. So, this statement is incorrect. \item (2) Cetyltrimethyl ammonium bromide is used in hair conditioners: Cetyltrimethyl ammonium bromide (CTAB) is a cationic surfactant. Cationic surfactants are commonly used in hair conditioners because their positively charged head groups bind to the negatively charged surface of hair, reducing static electricity and providing a smooth feel. So, this statement is correct. \item (3) Liquid dish washing detergents are anionic type: While some liquid dishwashing detergents may contain anionic surfactants, many are non-ionic or a mixture of anionic and non-ionic surfactants to effectively remove grease and food particles and to be gentle on hands. Anionic surfactants like sodium lauryl sulfate (SDS) are common in laundry detergents. So, this statement is not universally true and likely incorrect as a general statement. \item (4) Synthetic detergents cannot be used in hard water: Synthetic detergents are designed to work well in hard water because their calcium and magnesium salts are soluble and do not form scum, unlike soaps. So, this statement is incorrect.
\end{itemize} Step 2: Identify the correct statement.
Based on the evaluation, the correct statement is (2). Final Answer:
15
PYQ 2023
medium
chemistryID: ap-eapce
Which of the following is an example of a multi molecular colloid?
1
Sulphur sol
2
Starch sol
3
Natural rubber sol
4
Soap sol
Official Solution
Correct Option:
(1)
Colloids can be classified based on the nature of the dispersed phase particles into multimolecular, macromolecular, and associated colloids. - **Multimolecular colloids:** These colloids are formed by the aggregation of a large number of atoms or small molecules (diameter<1 nm) to form colloidal particles having a size in the colloidal range (1-1000 nm). Examples include sols of gold, sulphur, and metal sulphides. - **Macromolecular colloids:** In these colloids, the dispersed phase particles are macromolecules (large molecules) having colloidal dimensions. These macromolecules have high molecular masses. Examples include starch, proteins, cellulose, and synthetic polymers like rubber and nylon. - **Associated colloids (Micelles):** These colloids behave as normal strong electrolytes at low concentrations but exhibit colloidal properties at higher concentrations due to the formation of aggregates of molecules called micelles. Examples include soaps and detergents. Based on these definitions: - **Sulphur sol:** Sulphur sol is formed by the aggregation of a large number of molecules. Thus, it is a multimolecular colloid. - **Starch sol:** Starch is a macromolecule. Its sol is a macromolecular colloid. - **Natural rubber sol:** Natural rubber is a polymer, a macromolecule. Its sol is a macromolecular colloid. - **Soap sol:** Soap forms micelles at higher concentrations, which are associated colloids. Therefore, the example of a multimolecular colloid among the given options is Sulphur sol.
16
PYQ 2023
medium
chemistryID: ap-eapce
Identify the macromolecular colloids from the list given below:
I. Synthetic rubber II. Rhombic sulphur III. Sodium stearate
IV. Cellulose V. Enzymes VI. Sodium lauryl sulphate
1
I, III \& VI only
2
II, III \& IV only
3
III, IV \& V only
4
I, IV \& V only
Official Solution
Correct Option:
(4)
Macromolecular colloids are those where macromolecules form the dispersed phase.
- Synthetic rubber (I): polymer → macromolecular colloid
- Cellulose (IV): natural polymer → macromolecular colloid
- Enzymes (V): biological macromolecules → macromolecular colloids
- Sodium stearate and sodium lauryl sulphate are associated colloids.
- Rhombic sulphur is not colloidal.
17
PYQ 2023
medium
chemistryID: ap-eapce
5.0 mL of [AgI] / Ag sol is coagulated by the addition of 15 mL of 0.001 M potassium iodide solution. The flocculation value of potassium iodide is
1
6
2
5
3
3
4
4
Official Solution
Correct Option:
(3)
Flocculation value =
Millimoles of KI = mmol
Flocculation value = mol/L or 3 mmol/L
18
PYQ 2024
medium
chemistryID: ap-eapce
Identify the method of preparation of a colloidal sol from the following:
1
Ultrafiltration
2
Peptisation
3
Dialysis
4
Electro-dialysis
Official Solution
Correct Option:
(2)
Step 1: Understanding Peptisation Peptisation is the process of converting a precipitate into a colloidal solution by adding a suitable electrolyte. Step 2: Explanation - In peptisation, the electrolyte adsorbs onto the surface of the precipitate, causing it to break into smaller particles that remain suspended in the solution. - It is widely used in the preparation of colloidal sols. Thus, the correct answer is Peptisation.
19
PYQ 2024
medium
chemistryID: ap-eapce
Match List - I with List -
1
I-B, II-A, III-C, IV-D
2
I-A, II-C, III-D, IV-B
3
I-A, II-B, III-C, IV-D
4
I-A, II-D, III-B, IV-C
Official Solution
Correct Option:
(2)
- Colloidal antimony is used to treat Kalaazar (A). - Silver sol is used in Eye lotion (C).
- Milk of magnesia is an antacid used for stomach disorders (D).
- Gold sol is used in intramuscular injections (B). Thus, the correct match is: I-A, II-C, III-D, IV-B. \bigskip
20
PYQ 2025
medium
chemistryID: ap-eapce
Match the following:
List-I (Sol)
List-II (Method of preparation)
A)
I) Bredig's arc method
B)
II) Oxidation
C)
III) Hydrolysis
D)
IV) Double decomposition
1
A-III, B-II, C-IV, D-I
2
A-I, B-III, C-IV, D-II
3
A-IV, B-I, C-II, D-III
4
A-IV, B-III, C-I, D-II
Official Solution
Correct Option:
(3)
- A) As₂S₃ is prepared by double decomposition (IV). - B) Au is prepared by Bredig's arc method (I). - C) S is prepared by oxidation (II). - D) Fe(OH)₃ is prepared by hydrolysis (III).
21
PYQ 2025
medium
chemistryID: ap-eapce
In a colloidal solution, both the dispersed phase and dispersion medium are in liquid phase. What is the type of colloid?
1
gel
2
emulsion
3
foam
4
aerosol
Official Solution
Correct Option:
(2)
Colloidal solutions are classified based on the physical state of the dispersed phase and the dispersion medium.
- Gel: Dispersed phase is liquid, dispersion medium is solid. (e. g. , jelly, cheese, butter).
- Emulsion: Dispersed phase is liquid, dispersion medium is liquid. (e. g. , milk, hair cream, mayonnaise).
- Foam: Dispersed phase is gas, dispersion medium is liquid. (e. g. , whipped cream, soap lather). (Solid foam: Dispersed phase gas, medium solid, e. g. , pumice stone, styrofoam).
- Aerosol: Dispersed phase is solid or liquid, dispersion medium is gas. - Liquid in Gas (e. g. , fog, mist, clouds, hair sprays). - Solid in Gas (e. g. , smoke, dust). The question states that both the dispersed phase and the dispersion medium are in the liquid phase.
This type of colloid is called an emulsion.
This matches option (2).
22
PYQ 2025
medium
chemistryID: ap-eapce
In each of four separate beakers (I, II, III, IV), X mL of 1M Fe O ·xH O colloidal solution is present. Equal volume and equal concentration of KCl, K [Fe(CN) ], K PO and K SO was added into I, II, III and IV respectively.
The efficiency of precipitations in these beakers follows the order
1
II > III > IV > I
2
II > III > I > IV
3
I > IV > III > II
4
III > IV > I > II
Official Solution
Correct Option:
(1)
Step 1: Apply Hardy–Schulze rule. According to this rule, the coagulating power of an electrolyte increases with the valency of the oppositely charged ion. Step 2: Identify the charge on Fe O ·xH O. This colloid is positively charged, so we need to focus on the anions of the added salts. Step 3: List anions and their valency: KCl → Cl (valency = 1) K [Fe(CN) ] → [Fe(CN) ] (valency = 4) K PO → PO (valency = 3) K SO → SO (valency = 2) Step 4: Order of coagulation power: Higher the valency, greater the precipitation: [Fe(CN) ] > PO > SO > Cl So, order of beakers is: II > III > IV > I
23
PYQ 2025
medium
chemistryID: ap-eapce
Which one of the following is not the correct characteristic property of physical adsorption?
1
It is not specific in nature
2
Enthalpy of adsorption of this is low
3
It increases with increase of temperature
4
It is a multilayer adsorption under high pressure
Official Solution
Correct Option:
(3)
Step 1: Understand physical adsorption characteristics. - Physical adsorption is non-specific in nature. - Enthalpy of adsorption is low (typically 20–40 kJ/mol). - It forms multilayers especially under high pressure. - However, it decreases with increase in temperature, since it is an exothermic process (Le Chatelier’s principle). Step 2: Identify the incorrect statement. Option (3) says physical adsorption increases with temperature, which contradicts the above point. Hence, it is the incorrect statement.
24
PYQ 2025
medium
chemistryID: ap-eapce
Match the following
1
A-III, B-I, C-II, D-IV
2
A-III, B-I, C-IV, D-II
3
A-IV, B-II, C-I, D-III
4
A-II, B-I, C-IV, D-III
Official Solution
Correct Option:
(1)
Let's match each colloidal solution in List-I with its appropriate use in List-II. A) Colloidal antimony: Colloidal preparations of antimony have been historically used in medicine for the treatment of parasitic diseases, most notably for Kala-azar (leishmaniasis).
A - III B) Argyrol: Argyrol is a brand name for a colloidal solution of silver protein. Due to its antiseptic properties, it was widely used as a topical antiseptic, particularly as an eye lotion for treating eye infections.
B - I C) Colloidal gold: Colloidal gold has diverse applications. In the context of medicine, it has been explored for various therapeutic purposes, including as an intramuscular injection for certain conditions (though its use has evolved with modern medicine, historical and experimental uses include this application).
C - II D) Milk of magnesia: Milk of magnesia is an aqueous suspension (a type of colloidal solution) of magnesium hydroxide, Mg(OH) . It is a common antacid and laxative, primarily used to relieve heartburn, indigestion, and constipation, which are forms of stomach disorders.
D - IV Summary of Matches:
A - III
B - I
C - II
D - IV Comparing this with the given options, Option (1) matches our derived set of correspondences. The final answer is .
25
PYQ 2025
medium
chemistryID: ap-eapce
The critical micelle concentration (CMC) of a soap solution is . Identify the correct statements about this solution. [I.] The micelle is stable if the soap solution concentration is
[II.] The micelle is stable if the soap solution concentration is higher than
[III.] Micelles are also known as associated colloids.
1
I, II, III
2
I, II only
3
I, III only
4
II, III only
Official Solution
Correct Option:
(4)
Step 1: Evaluate the statements
Statement I is incorrect: Micelles do not form if the concentration is below the CMC (i.e., at , which is much lower than the given CMC).
Statement II is correct: Micelles form and are stable only when the concentration is above the CMC.
Statement III is correct: Micelles are indeed classified as associated colloids due to their structure and behavior.
Final Answer:
II, III only
26
PYQ 2025
medium
chemistryID: ap-eapce
The adsorption of a gas on a solid surface follows Freundlich adsorption isotherm.At (K), the gas pressure is atm. What is the value of ? ( and = constant)
1
2
3
4
Official Solution
Correct Option:
(4)
Step 1: Freundlich Adsorption Isotherm The Freundlich adsorption isotherm is given by: where:
- is the gas pressure,
- is a constant,
- . Step 2: Substituting Values Approximating : Conclusion Thus, the correct answer is:
27
PYQ 2025
medium
chemistryID: ap-eapce
In a Freundlich adsorption isotherm, if the slope is unity and k is 0.1, the extent of adsorption at 2 atm is (log 2 = 0.30)
1
0.6
2
0.4
3
0.2
4
0.8
Official Solution
Correct Option:
(3)
The Freundlich adsorption isotherm is given by: $ x m p k n k = 0.1 x/m p=2 $
28
PYQ 2025
easy
chemistryID: ap-eapce
Identify the correct statements from the following (only one): I) Sulphur sol is an example of multimolecular colloid. II) Starch sol is an example of associated colloid. III) Artificial rubber is an example of macromolecular colloid.
Official Solution
Correct Option:
(1)
29
PYQ 2025
medium
chemistryID: ap-eapce
Adsorption of a gas on solids follows the Freundlich adsorption isotherm. The graph drawn between log (on the y-axis) and log (on the x-axis) is a straight line with a slope equal to 3 and an intercept equal to 0.30. What is the value of at a pressure of 2 atm?
(Given: log 2 = 0.3)
1
48
2
32
3
16
4
8
Official Solution
Correct Option:
(3)
Step 1: Understand the Freundlich adsorption isotherm equation.
The Freundlich adsorption isotherm is empirically expressed as:
$ x m p K 1/n \log \left(\frac{x}{m}\right) \log p y = c + mx' m' y = \log \left(\frac{x}{m}\right) x' = \log p m' \frac{1}{n} c \log K p = 2 \log 2 = 0.3 K 1/n \frac{1}{n} \log K \log 2 = 0.3 \log K = 0.30 K = \operatorname{antilog}(0.30) K = 2 \frac{x}{m} K 1/n p \boxed{16}$.
30
PYQ 2025
medium
chemistryID: ap-eapce
The adsorption of a gas on a solid surface follows Freundlich adsorption isotherm.At (K), the gas pressure is atm. What is the value of ? ( and = constant)
1
2
3
4
Official Solution
Correct Option:
(4)
Step 1: Freundlich Adsorption Isotherm The Freundlich adsorption isotherm is given by: where:
- is the gas pressure,
- is a constant,
- . Step 2: Substituting Values Approximating : Conclusion Thus, the correct answer is:
31
PYQ 2025
medium
chemistryID: ap-eapce
Identify the catalytic reaction in which both reactants are in different phases.
1
Ammonia synthesis by Haber process
2
Synthesis of sulphur trioxide by lead chamber process
3
Hydrogenation of vegetable oils
4
Hydrolysis of methyl acetate
Official Solution
Correct Option:
(3)
Hydrogenation of vegetable oils involves gaseous hydrogen and liquid oil in the presence of solid Ni catalyst. This is a heterogeneous catalytic reaction with reactants in different phases.
Other processes involve homogeneous or single-phase reactions.
32
PYQ 2025
medium
chemistryID: ap-eapce
In a colloidal solution, both the dispersed phase and dispersion medium are in liquid phase. What is the type of colloid?
1
gel
2
emulsion
3
foam
4
aerosol
Official Solution
Correct Option:
(2)
Colloidal solutions are classified based on the physical state of the dispersed phase and the dispersion medium.
- Gel: Dispersed phase is liquid, dispersion medium is solid. (e. g. , jelly, cheese, butter).
- Emulsion: Dispersed phase is liquid, dispersion medium is liquid. (e. g. , milk, hair cream, mayonnaise).
- Foam: Dispersed phase is gas, dispersion medium is liquid. (e. g. , whipped cream, soap lather). (Solid foam: Dispersed phase gas, medium solid, e. g. , pumice stone, styrofoam).
- Aerosol: Dispersed phase is solid or liquid, dispersion medium is gas. - Liquid in Gas (e. g. , fog, mist, clouds, hair sprays). - Solid in Gas (e. g. , smoke, dust). The question states that both the dispersed phase and the dispersion medium are in the liquid phase.
This type of colloid is called an emulsion.
This matches option (2).
33
PYQ 2025
medium
chemistryID: ap-eapce
Identify the correct statements from the following:
I) In adsorption process, both enthalpy and entropy decrease.
II) In general, physisorption is an irreversible process.
III) The catalyst used in the decomposition of potassium chlorate is manganese dioxide.
1
I, II, III
2
I, II only
3
I, III only
4
II, III only
Official Solution
Correct Option:
(3)
In adsorption, the process is exothermic and leads to decreased entropy (randomness). Manganese dioxide is used as catalyst in decomposition of KClO . However, physisorption is usually reversible, not irreversible.
34
PYQ 2025
medium
chemistryID: ap-eapce
Which of the following is an example of a positively charged sol?
1
As S sol
2
Congo red sol
3
TiO sol
4
Gelatin sol
Official Solution
Correct Option:
(3)
Positively charged sols include metal oxides like TiO , Fe(OH) , and Al(OH) which acquire a positive charge in water due to adsorption of H ions. TiO sol is a well-known positively charged sol.
About Surface Chemistry - AP-EAPCET
Surface Chemistry is a vital chapter for AP-EAPCET aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.
By rigorously practicing the previous year questions associated with this chapter, you can identify high-yield topics, understand the examiner's perspective, and boost your confidence during the actual exam.
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