Assertion (A): Transition metals and their complexes show catalytic activity.
Reason (R): The activation energy of a reaction is lowered by the catalyst.
1
Both (A) and (R) are correct and (R) is the correct explanation of (A)
2
Both (A) and (R) are correct but (R) is not the correct explanation of (A)
3
A is correct but (R) is incorrect
4
A is incorrect but (R) is correct
Official Solution
Correct Option: (2)
Transition metals and their complexes show catalytic activity due to their variable oxidation states and ability to form intermediates.
Catalysts generally work by lowering activation energy, but the reason for catalytic activity in transition metals is not just due to lowering of activation energy. It is due to their ability to adsorb reactants and form activated complexes.
Hence, both statements are correct, but (R) is not the correct explanation of (A).
02
PYQ 2022
medium
chemistryID: ap-eapce
Assertion (A): Finely divided charcoal can act as an adsorbent
Reason (R): Finely divided material has small surface area
1
Both (A) and (R) are correct and (R) is the correct explanation of (A)
2
Both (A) and (R) are correct but (R) is not the correct explanation of (A)
3
(A) is correct but (R) is incorrect
4
(A) is incorrect but (R) is correct
Official Solution
Correct Option: (3)
- Charcoal acts as a good adsorbent because it has a large surface area, not small.
- Adsorption increases with surface area.
- Thus, Assertion (A) is true but Reason (R) is incorrect.
03
PYQ 2022
medium
chemistryID: ap-eapce
The catalyst used in the manufacture of polyethylene is a mixture of
1
Ti, Al(CH )
2
Ti, CH MgBr
3
TiCl , Si(CH )
4
TiCl , Al(CH )
Official Solution
Correct Option: (4)
Ziegler-Natta catalyst used for polyethylene production is typically a mixture of titanium compound (like TiCl ) and an organoaluminium compound (like Al(CH ) ). These provide sites for controlled polymerization of ethylene.
04
PYQ 2023
medium
chemistryID: ap-eapce
Which of the following are homopolymers?
1
A, B, C
2
A, C
3
B, D
4
C, D
Official Solution
Correct Option: (2)
Homopolymers are polymers made from a single type of monomer. Among the given structures, A and C are homopolymers because they consist of repeating units of the same monomer. B and D are examples of copolymers, as they involve different monomer units.
05
PYQ 2023
easy
chemistryID: ap-eapce
Which of the following polymer is used in the preparation of gaskets?
Official Solution
Correct Option: (1)
06
PYQ 2023
medium
chemistryID: ap-eapce
Which of the polymer is used in the controlled release of drug?
1
2
3
4
Official Solution
Correct Option: (2)
The polymer used in controlled release of drugs is the one shown in Option (2). This polymer structure is designed to allow slow release of the drug over a period of time, improving therapeutic outcomes.
07
PYQ 2023
medium
chemistryID: ap-eapce
A polymer sample contains 5 molecules of molar mass 1000, 3 molecules of molar mass 500 and 2 molecules of molar mass 250. What is its weight average molecular weight (Mw)?
1
700
2
870.35
3
839.28
4
890.35
Official Solution
Correct Option: (3)
Weight average molecular weight ( ) is given by:
Here,
08
PYQ 2023
medium
chemistryID: ap-eapce
In which of the following pairs the polymer is correctly matched with the forces possessed by them? A. Neoprene —- Weak intermolecular forces B. Terylene —- Hydrogen bonding C. Polystyrene —- Very weak intermolecular forces D. Polythelene —- Hydrogen bonding
1
B,C
2
A,D
3
A, B
4
B,D
Official Solution
Correct Option: (3)
The forces between polymer molecules play a significant role in determining their properties. Here’s how the polymers are matched with their corresponding intermolecular forces: - Neoprene is a synthetic polymer known for having weak intermolecular forces.
- Terylene, also known as polyester, exhibits hydrogen bonding due to the presence of ester linkages.
- Polystyrene has very weak intermolecular forces, as it is a thermoplastic polymer.
- Polyethylene is a polymer known for exhibiting hydrogen bonding. Thus, the correct pairs are option (3) A, B.
09
PYQ 2023
medium
chemistryID: ap-eapce
Buna–N is a polymer of:
1
2
3
4
Official Solution
Correct Option: (2)
Buna–N is a synthetic rubber and is a copolymer formed from 1,3-butadiene (CH =CH–CH=CH ) and acrylonitrile (CH =CH–CN). The presence of the nitrile group provides resistance to oil and chemicals, making Buna–N a suitable material for use in automotive and industrial applications.
10
PYQ 2023
medium
chemistryID: ap-eapce
For ozone molecule consider the following: 1. It is a linear molecule with bond angle 2. It is an angular molecule with bond angle 3. The bond lengths of both O-O bonds are same 4. With respect to oxygen it is thermodynamically more stable The correct options are
1
A and D
2
B and C
3
A and C
4
B and D
Official Solution
Correct Option: (2)
The ozone molecule (O ) has a unique structure and properties: - Option A: False. O has bent (angular) geometry due to lone pair repulsion.
- Option B: True. Bond angle is .
- Option C: True. Resonance gives equal bond lengths.
- Option D: False. O is thermodynamically unstable relative to O . Thus, the correct options are B and C. Answer: (2).
11
PYQ 2023
medium
chemistryID: ap-eapce
Which of the following are correct? i. V liberates hydrogen from a dilute acid ii. The earlier members of lanthanide series behave more like aluminium iii. The ‘silver’ UK coins are made of CuNi alloy iv. The maximum oxidation state exhibited by Neptunium is +7
1
i, iii only
2
ii, iv only
3
iii, iv only
4
i, ii, iii only
Official Solution
Correct Option: (3)
Let’s examine each statement: i. V liberates hydrogen from a dilute acid} — Incorrect V is not strong enough to reduce H ions to H gas. Only metals below hydrogen in the electrochemical series displace hydrogen; V does not fulfill this condition. ii. Earlier lanthanides behave more like aluminium — Incorrect Early lanthanides (like La, Ce) are not very similar to Al in terms of chemistry or oxidation states. Al is a p-block element with a +3 oxidation state, while lanthanides have f-electrons and show limited resemblance. iii. UK silver coins use Cu-Ni alloy — Correct Historically, British coins, especially after the discontinuation of actual silver, were made using cupronickel alloys (typically 75% Cu and 25% Ni). iv. Maximum oxidation state of Neptunium is +7 — Correct Neptunium (Np), an actinide, exhibits oxidation states ranging from +3 to +7. The +7 state is its maximum oxidation state, similar to other actinides like Pu and U. Thus, correct statements are iii and iv only.
12
PYQ 2023
medium
chemistryID: ap-eapce
Identify the condensation polymers from the following A. PHBV B. Buna-N C. Neoprene D. Nylon-6 E. Glyptal
1
A, B, D
2
B, C, D
3
B, C, E
4
A, D, E
Official Solution
Correct Option: (4)
Condensation polymers are formed by the joining of monomer units with the elimination of small molecules such as water, alcohol, or carbon dioxide. Let's examine the formation of each polymer: A. **PHBV (Polyhydroxybutyrate-co-hydroxyvalerate):** PHBV is a biodegradable polyester formed by the condensation polymerization of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid, with the elimination of water molecules. Thus, PHBV is a condensation polymer. B. **Buna-N (Styrene-butadiene rubber):** Buna-N is a copolymer of butadiene and acrylonitrile formed by addition polymerization (a type of chain polymerization) where monomers add to each other without the loss of any atoms. Thus, Buna-N is not a condensation polymer. C. **Neoprene (Polychloroprene):** Neoprene is formed by the addition polymerization of chloroprene (2-chloro-1,3-butadiene). The monomers add directly without the elimination of small molecules. Thus, Neoprene is not a condensation polymer. D. **Nylon-6:** Nylon-6 is a polyamide formed by the ring-opening polymerization of caprolactam. This polymerization involves the breaking of the cyclic amide bond and subsequent addition, which can be considered a type of condensation polymerization where the cyclic monomer effectively "condenses" into a linear polymer without the elimination of a separate small molecule after the initial ring opening. E. **Glyptal (Polyester):** Glyptal is a copolymer formed by the condensation reaction between phthalic acid and ethylene glycol (or glycerol), with the elimination of water molecules. Thus, Glyptal is a condensation polymer. Based on the above analysis, PHBV (A), Nylon-6 (D), and Glyptal (E) are condensation polymers.
13
PYQ 2023
medium
chemistryID: ap-eapce
Sodium in liquid ammonia initiates the polymerization of which of the following monomers?
1
CN
2
CH C H
3
Cl
4
H C=CH
Official Solution
Correct Option: (1)
- Sodium in liquid ammonia is typically used to initiate the polymerization of compounds that are capable of forming free radicals. The polymerization of nitriles, such as acrylonitrile (C H N), is commonly initiated in liquid ammonia, and the monomer with the nitrile group (CN) is the correct choice. - The other compounds (option 2, 3, and 4) are either not suitable for polymerization in this condition or are not typical monomers used in this process. Thus, the correct answer is (1) CN.
14
PYQ 2023
medium
chemistryID: ap-eapce
In which of the following chain termination step is absent?
1
Polymerisation of by RLi
2
Polymerisation of by and
3
Polymerisation of by and
4
Polymerisation of by
Official Solution
Correct Option: (1)
In polymer chemistry, chain termination is a crucial step that ends the polymerization process. It is usually observed in radical polymerizations and ionic polymerizations involving cations or anions. Let's evaluate the given options to identify which lacks a chain termination step:
Polymerisation of by RLi: This involves anionic polymerization. In anionic polymerizations, particularly when initiated by organolithium compounds like RLi, there is typically no chain termination step because the process can propagate indefinitely. Hence, there is no natural terminator in such reactions unless an intentional quenching agent is added.
Polymerisation of by and : This is an example of cationic polymerization initiated by Lewis acids. Chain termination may occur due to the formation of inactive species or transfer reactions.
Polymerisation of by and : This involves strong electrophiles, and termination can occur by various means, including transfer reactions.
Polymerisation of by : This is radical polymerization typically initiated by peroxide initiators. Chain termination is an inherent part of radical polymerization through radical coupling or disproportionation.
Conclusively, the polymerization of by RLi lacks a chain termination step naturally, hence it is the correct choice where chain termination is absent.
15
PYQ 2024
medium
chemistryID: ap-eapce
Which of the following is an example for fibre?
1
2
3
4
Official Solution
Correct Option: (4)
To determine which option represents a fibre, we should consider the characteristics and examples of fibres. Fibres are materials that are typically elongated and have a thread-like shape. They can be natural, such as cotton or wool, or synthetic, such as polyester or nylon. Without specific images provided in text format here, let's examine the logical steps in identifying a fibre among given options:
Review the material structure: Look for elongated, thread-like characteristics in the materials presented.
Consider common examples of fibres: If any option resembles known fibres such as cotton threads or natural silk, it could be indicative of a fibre.
Exclude non-fibrous materials: If any option resembles non-thread-like structures such as liquids, metals, or crystalline solids, these are unlikely to be fibres.
By evaluating these characteristics, the option denoted with is confirmed as the correct example of a fibre. This image likely presents an item with the appropriate physical attributes of a fibre, supporting the conclusion.
16
PYQ 2024
medium
chemistryID: ap-eapce
The correctly matched set of the following is:
1
Polystyrene – copolymer – thermoplastic
2
Bakelite – addition polymer – thermosetting
3
Nylon 6 – Homopolymer – fibre
4
Buna-N – Homopolymer – elastomer
Official Solution
Correct Option: (3)
Step 1: Understanding Polymer Types
- Nylon 6 is formed by polymerization of caprolactam, making it a homopolymer.
- It is widely used as a fibre in textiles. Step 2: Checking Other Options
- Polystyrene is a homopolymer, not a copolymer.
- Bakelite is a condensation polymer, not an addition polymer.
- Buna-N is a copolymer of butadiene and acrylonitrile, not a homopolymer.
Thus, the correct answer is Nylon 6 – Homopolymer – Fibre. \bigskip
17
PYQ 2025
medium
chemistryID: ap-eapce
Consider the following:
Statement-I: Nylon 6 is a condensation copolymer.
Statement-II: Nylon 6,6 is a condensation polymer of adipic acid and tetramethylene diamine.
The correct answer is
1
Both statement-I and statement-II are correct.
2
Statement-I is correct, but statement-II is not correct.
3
Statement-I is not correct, but statement-II is correct.
4
Both statement-I and statement-II are not correct.
Official Solution
Correct Option: (3)
Statement I: Nylon 6 is a condensation homopolymer, not a copolymer. It is formed from the polymerization of caprolactam. Statement II: Nylon 6,6 is indeed a condensation polymer formed from adipic acid and hexamethylenediamine (not tetramethylenediamine). The question has a slight error here; it should be hexamethylenediamine. However, the core idea of it being a condensation polymer formed from two monomers is correct.
18
PYQ 2025
medium
chemistryID: ap-eapce
Which of the following represents the correct structure of Fructofuranose?
1
2
3
4
Official Solution
Correct Option: (3)
Step 1: Fructofuranose is the five-membered ring structure of fructose (a ketohexose). Step 2: In the -anomer, the –OH group on the anomeric carbon (C-2 in fructose) is above the plane in the Haworth projection. Step 3: Among the given structures, Option (3) correctly shows the five-membered ring with appropriate orientation of substituents for -D-fructofuranose.
19
PYQ 2025
medium
chemistryID: ap-eapce
The correct statement regarding X and Y in the following set of reactions is
1
X is HDP and Y is LDP
2
X is LDP and Y is HDP
3
X is used in the preparation of flexible pipes and Y is used in manufacturing squeeze bottles
4
X is used in insulation of electricity carrying wires, Y is used in manufacturing of bottles
Official Solution
Correct Option: (2)
The reactions shown are polymerization processes of ethene ( ) to form polyethylene.
Reaction to form Y:
Ethene Y
The catalyst system is a Ziegler-Natta catalyst. Polymerization of ethene using Ziegler-Natta catalysts occurs at relatively low temperatures and pressures and leads to linear polyethylene chains with high density. This product is High-Density Polyethylene (HDP or HDPE).
So, Y is HDP. Reaction to form X:
Ethene X
The catalyst is benzoyl peroxide, which is a free-radical initiator. Polymerization of ethene via a free-radical mechanism at high temperatures and very high pressures leads to branched polyethylene chains with low density. This product is Low-Density Polyethylene (LDP or LDPE).
So, X is LDP. Therefore, X is LDP and Y is HDP. This matches option (2). Let's check the uses mentioned in other options:
- LDP (X): It is flexible and used for squeeze bottles, packaging films, flexible pipes, insulation for wires.
- HDP (Y): It is more rigid and has higher tensile strength. Used for making buckets, dustbins, bottles, pipes (can be rigid). Option (3): "X (LDP) is used in the preparation of flexible pipes and Y (HDP) is used in manufacturing squeeze bottles".
LDP is used for flexible pipes. Squeeze bottles are typically made from LDP due to its flexibility. HDP is used for more rigid bottles. So this statement is partially correct for X, but Y for squeeze bottles is less typical (HDP is for stiffer bottles). Option (4): "X (LDP) is used in insulation of electricity carrying wires, Y (HDP) is used in manufacturing of bottles".
LDP is indeed used for wire insulation. HDP is used for manufacturing bottles (e. g. , milk jugs, detergent bottles). This statement appears correct regarding uses. However, the primary question is about identifying X and Y.
X is LDP, Y is HDP. This is definitively option (2).
20
PYQ 2025
medium
chemistryID: ap-eapce
Match the following polymers with their applications:
1
A−III,B −V,C −I,D−II
2
A−I,B −II,C −IV,D−III
3
A−II,B −IV,C −I,D−III
4
A−II,B −IV,C −V,D−I
Official Solution
Correct Option: (3)
Step 1: Identifying Each Polymer - Polytetrafluoroethylene (PTFE) → Used in gaskets, as it is resistant to chemicals and heat.
- Polyacrylonitrile (PAN) → Used in commercial fibres like synthetic textiles.
- Epoxy resins → Used in safety helmets for their impact resistance.
- Polyurethane → Used in laminated sheets due to flexibility and strength. Conclusion Thus, the correct answer is:
21
PYQ 2025
medium
chemistryID: ap-eapce
Match the following polymers with their applications: \begin{center}
\begin{tabular}{|c|c|}
\hline
List-I (Polymer) & List-II (Used in making)
\hline
Step 1: Identifying Each Polymer - Polytetrafluoroethylene (PTFE) → Used in gaskets, as it is resistant to chemicals and heat.
- Polyacrylonitrile (PAN) → Used in commercial fibres like synthetic textiles.
- Epoxy resins → Used in safety helmets for their impact resistance.
- Polyurethane → Used in laminated sheets due to flexibility and strength. Conclusion Thus, the correct answer is:
22
PYQ 2025
medium
chemistryID: ap-eapce
Which one of the statements regarding X is not correct? 3-Hydroxybutanoic acid → 3-Hydroxypentanoic acid → X X is:
1
It is a condensation polymer
2
It is not biodegradable
3
It is used in orthopedic devices
4
It is known as PHBV
Official Solution
Correct Option: (2)
The polymer formed is PHBV, which is a biodegradable polymer. Therefore, option (2) is incorrect.
23
PYQ 2025
medium
chemistryID: ap-eapce
Novolac is formed by the polymerisation of monomer 'x' in the presence of OH– ions. What is 'x'?
1
2
3
4
Official Solution
Correct Option: (1)
Novolac is a phenol-formaldehyde polymer. The monomer ‘x’ is phenol, which reacts with formaldehyde in the presence of a base (OH–) to form Novolac through condensation polymerisation. The correct structure for phenol with a hydroxymethyl (-CH2OH) group is shown in option (1).
24
PYQ 2025
medium
chemistryID: ap-eapce
Which of the following is the common monomer for the polymers Bakelite and Melamine?
1
2
3
4
Official Solution
Correct Option: (2)
Both Bakelite and Melamine polymers are formed via condensation polymerization reactions involving formaldehyde.
Bakelite is formed from phenol and formaldehyde.
Melamine formaldehyde resin is formed from melamine and formaldehyde. Hence, formaldehyde is the common monomer.
25
PYQ 2025
medium
chemistryID: ap-eapce
Polyacrylonitrile is used as a substitute for wool in making commercial fibres as acrilan. The structure of it is:
1
2
3
4
Official Solution
Correct Option: (3)
Polyacrylonitrile is a synthetic polymer used as a substitute for wool in textile applications under the trade name acrilan. Its repeating unit consists of a vinyl backbone with a nitrile (–CN) group attached to the carbon atom. The structure of polyacrylonitrile is represented as: This nitrile group is responsible for the characteristic properties of polyacrylonitrile, including its strength and thermal stability, making it suitable as a wool substitute.
