Question map
In which of the following are hydrogels used ? 1. Controlled drug delivery in patients 2. Mobile air-conditioning systems 3. Preparation of industrial lubricants Select the correct answer using the code given below :
Explanation
The correct answer is option A (1 only).
Hydrogels have emerged as versatile and promising platforms for drug delivery[1], and pH-sensitive and/or temperature sensitive hydrogels can be used for site-specific controlled drug delivery[2]. Early PEG hydrogels were applied mostly as controlled drug delivery systems and as anti-adhesive biomaterials[3]. This clearly establishes that hydrogels are indeed used in controlled drug delivery in patients (Statement 1 is correct).
However, the provided sources contain no information supporting the use of hydrogels in mobile air-conditioning systems (Statement 2) or in the preparation of industrial lubricants (Statement 3). The one reference to mobile services in the documents relates to Internet of Things applications with sensors or drones, which is unrelated to hydrogels or air-conditioning systems.
Since only Statement 1 is verifiable and correct based on the available evidence, the answer is option A (1 only). For UPSC preparation, remember that hydrogels are primarily biomedical materials known for their high water content and applications in drug delivery, wound dressing, and tissue engineering.
Sources- [1] http://www.nanochemres.org/article_206449.html
- [3] https://www.sciencedirect.com/science/article/pii/0142961284900632
PROVENANCE & STUDY PATTERN
Full viewThis question exposes the limits of static reading. You cannot find 'Mobile AC' in a standard book index under Hydrogels. You must derive the answer from the material's physics: Hydrogels absorb water → Water evaporation causes cooling → Used in ACs. It’s a test of scientific intuition, not memory.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Explicitly describes hydrogels as usable for site-specific controlled drug delivery.
- Mentions stimulus-responsive hydrogels (pH/temperature) which are applied for controlled release.
- States historical and practical use of PEG hydrogels primarily as controlled drug delivery systems.
- Directly ties a class of hydrogels (PEG) to controlled drug delivery applications.
- Is a dedicated chapter title indicating advances in hydrogel-based controlled drug-delivery systems.
- Shows focused scholarly attention on hydrogels for controlled drug delivery, supporting their use in this application.
Describes that different solvents/media (water, hydro-alcoholic extracts, oils, ghee, milk) have long been used as carriers for medicinal formulations.
A student could generalize that drug delivery often relies on varied carrier media and therefore consider hydrogels as another carrier medium to investigate for controlled delivery.
Defines that generic drugs may differ in inactive ingredients while retaining the same active ingredient, highlighting the role of formulation/excipients in how a drug is delivered.
Use this rule to explore whether hydrogels could function as a differing inactive matrix or excipient to modify release profiles in formulations.
Gives an example where patients (diabetics) are treated by injections of insulin, implying clinical need for controlled, timed, or route-specific delivery of therapeutics.
Combine this clinical need with knowledge of delivery systems to ask whether hydrogels can provide sustained or controlled release alternatives to injections.
Notes traditional use of plant materials for topical treatments and wound dressing, showing historical precedent for using physical matrices/materials in therapeutic application.
From this pattern, a student might investigate modern dressing materials (e.g., hydrogels) as matrices that can also release drugs at wound sites.
Mentions policy measures to promote R&D in the drug sector and exceptions for recombinant DNA technology, indicating an environment that supports pharmaceutical innovation.
A student could infer that novel delivery technologies (such as hydrogel-based systems) are plausible targets of contemporary pharmaceutical R&D to meet clinical needs.
States that air-conditioning systems and refrigeration release gases (CFCs) and that AC systems are a primary application area for cooling technology.
A student could note that ACs are a major domain for new materials/technologies (e.g., alternatives to refrigerants) and therefore investigate whether hydrogels have been explored as components (e.g., moisture/thermal management) in such systems.
Describes that refrigerants (HFCs) were developed as replacements for ozone-depleting chemicals, showing AC systems adopt alternative materials for environmental reasons.
A student could reason that, given AC technology seeks substitute materials for environmental and performance reasons, hydrogels might be evaluated as alternative or complementary materials (for humidity control, evaporative cooling, or thermal storage) in mobile AC.
Notes that cooling of moist air can produce fog/clouds subject to presence of hygroscopic nuclei, i.e., particles that promote condensation.
Knowing hydrogels are highly water-absorbing/hygroscopic, a student could hypothesize they might serve as hygroscopic media in systems that rely on moisture exchange or evaporative cooling in ACs and then check engineering sources for mobile AC use.
Defines humidity as water vapour in air, highlighting that controlling water vapour is a key aspect of air-conditioning.
Since hydrogels interact strongly with water vapour, a student could infer they might be useful in humidity-control components in AC systems (including mobile units) and look for applied examples or studies.
Discusses green building goals of using efficient equipment for air-conditioning and integrated design to reduce environmental impact.
A student could extend this to consider that novel materials (like hydrogels) may be investigated for efficient or low-energy AC solutions (including for vehicles or mobile applications) and then search technical literature on such innovations.
Lists paraffin, wax and oils explicitly as materials used as lubricants and in lubricant-related products.
A student could use this pattern (lubricants = oil/wax-based substances) plus basic knowledge that hydrogels are water-swollen polymers to question whether a water-rich material fits typical lubricant compositions.
States that petroleum by-products are processed into lubricants, vaseline, wax and greases—showing a petrochemical basis for many industrial lubricants.
Combine this rule with the fact that hydrogels are not petroleum-derived to assess how common it would be for hydrogels to serve as industrial lubricants.
Enumerates a long list of petroleum products including lubricant oils, greases, paraffin and wax, emphasizing oil-based formulations for many applications.
Use this as evidence that industrial lubricants are typically hydrocarbon/oil-based, so a student might look for exceptions or specialised aqueous polymer lubricants outside this dominant class.
Describes petroleum/mineral oil providing lubricants for machinery and as raw material for manufacturing industries, implying mineral oil is a common lubricant base.
A student could contrast mineral-oil-based lubricant prevalence with the chemistry of hydrogels (water/polymer networks) to judge plausibility of hydrogels being widely used industrially.
Notes water's role as a solvent in preparing medicinal formulations, giving an example of water-based formulation practice.
A student might extend this to consider that water-based (hydrogel-like) formulations do exist in other fields, and therefore investigate whether similar water-based systems are used specially (rather than commonly) as lubricants.
- [THE VERDICT]: **Logical Sitter**. While specific examples (Mobile AC) seem obscure, the 'All of the above' pattern for S&T applications holds true here.
- [THE CONCEPTUAL TRIGGER]: **Material Science (Polymers)**. Specifically, functional polymers used in everyday engineering and biotechnology.
- [THE HORIZONTAL EXPANSION]: **Hydrogel uses**: 1. Agriculture (Pusa Hydrogel for water retention). 2. Biomedical (Soft contact lenses, Wound dressings). 3. Hygiene (Superabsorbent polymers in diapers). **Sibling Material**: **Aerogels** (NASA uses for insulation, oil spill cleanup).
- [THE STRATEGIC METACOGNITION]: **Property-to-Function Mapping**. Instead of memorizing lists, memorize the property: 'Hydrophilic, biocompatible, viscoelastic network.' Then test the options: Does an AC need water management? Yes. Do lubricants need viscoelasticity? Yes. If the property fits, the use is valid.
Understanding medicinal solvents and carriers is essential to evaluating drug delivery systems such as hydrogels.
High-yield for questions on formulation science, traditional medicine practices, and pharmaceutical design; links pharmacology with public health and traditional systems. Mastery helps answer questions about how drugs are prepared, how delivery media affect efficacy, and policy issues around formulation standards.
- Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 9: The Amazing World of Solutes, Solvents, and Solutions > Our scientific heritage > p. 138
Knowledge of plant sources and active drug functions is fundamental when considering drug selection and formulation for controlled delivery.
Important for questions on drug discovery, pharmacognosy, and healthcare policy; connects biodiversity, medicinal chemistry, and clinical therapeutics. Useful for framing questions on sourcing active ingredients and formulation choices in drug delivery systems.
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 12: Major Crops and Cropping Patterns in India > Table III Pharmaceutical Plants, Drugs and Use > p. 90
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 12: Major Crops and Cropping Patterns in India > Table III Pharmaceutical Plants, Drugs and Use > p. 89
Distinguishing active ingredients from excipients/inactive carriers is central to assessing whether novel carriers like hydrogels change therapeutic equivalence.
Crucial for policymaking and regulatory questions (generic drugs, pricing, quality control); links pharmaceuticals, law, and economics. Helps answer exam items on drug regulation, substitution, and formulation-driven therapeutic outcomes.
- Indian Economy, Vivek Singh (7th ed. 2023-24) > Chapter 13: International Organizations > 13.10 Generic Drugs and Compulsory Licenses > p. 389
Air-conditioning systems commonly use refrigerants such as CFCs and HFCs, which have distinct effects on ozone depletion and global warming.
High-yield for environment and climate-change questions: understanding which refrigerants damage the ozone layer versus which are potent greenhouse gases is essential for policy and protocol discussions (e.g., Montreal Protocol, phase-downs). Connects to industrial regulation, mitigation measures, and energy sector impacts.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Chlorofl orocarbons (CFC) > p. 64
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Substitution for Ozone-Depleting Substances: > p. 257
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > here it is used? > p. 268
Refrigerants are released from air-conditioning equipment through leaks, servicing, and disposal, creating environmental release risks.
Important for questions on pollution control, lifecycle management, and regulatory interventions; helps frame mitigation strategies (leak prevention, safe servicing, end-of-life management) and links to waste and industrial safety topics.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Substitution for Ozone-Depleting Substances: > p. 257
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Chlorofl orocarbons (CFC) > p. 64
Cooling processes change water vapour content and can produce condensation (dew, fog), so humidity is central to AC operation and indoor comfort.
Useful for topics on urban comfort, indoor air quality, and energy-efficient building design; links thermodynamics (cooling, heat transfer) with building services and green-building measures.
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Non-Adiabatic Temperature Changes > p. 330
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > 24.1. Humidity > p. 325
Petroleum and its by-products are the main feedstock for producing lubricant oils and greases used in machinery.
High-yield for questions on energy and industrial inputs: explains why refineries are central to manufacturing and links to topics on petrochemicals and industrial supply chains. Helps answer questions on source-materials for industrial products and policy on energy security.
- INDIA PEOPLE AND ECONOMY, TEXTBOOK IN GEOGRAPHY FOR CLASS XII (NCERT 2025 ed.) > Chapter 5: Mineral and Energy Resources > Petroleum > p. 59
- NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 5: Print Culture and the Modern World > Petroleum > p. 115
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 8: Energy Resources > Petroleum > p. 9
Aerogels. Often called 'frozen smoke,' they are the lightest solid known. Prediction: 'In which of the following are Aerogels used? 1. Thermal insulation in space suits 2. Cleaning oil spills 3. Drug delivery.' (Answer: All).
The 'Scientific Possibility' Heuristic. In 'Applications of...' questions, if an option is not physically impossible (like 'Hydrogels for nuclear fusion'), assume it is true. Science is vast; if a researcher published a paper on it once, UPSC considers it a valid use. When in doubt, choose **D (All of the above)**.
GS3 Agriculture & Water Security. Hydrogels are a critical technology for **Dryland Farming** in India. Mentioning 'Pusa Hydrogel' (developed by IARI) in a Mains answer about irrigation efficiency adds specific technical weight.