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Q1Science·Chemistry in Everyday LifePYQ 2025
Consider the following substances:
1. Ethanol
2. Nitroglycerine
3. Urea
Coal gasification technology can be used in the production of how many of them?
- AOnly one
- BOnly two
- CAll threeCorrect
- DNone
Explanation
Correct. Coal gasification yields synthesis gas, which can be catalytically converted to ethanol, used to produce ammonia for urea, and processed into nitroglycerine precursors.
Why the other options are incorrect
- Option A
Coal gasification produces syngas (CO + H₂), which is a versatile feedstock for manufacturing all three substances, not just one.
- Option B
Syngas from coal gasification can be converted into ethanol, nitroglycerine (via intermediates), and urea (via ammonia synthesis), so two is an undercount.
- Option D
Coal gasification is a well-established route to multiple chemical feedstocks including all three listed substances.
Q2Science·Chemistry in Everyday LifePYQ 2023
Consider the following statements:
1. Carbon fibres are used in the manufacture of components used in automobiles and aircraft.
2. Carbon fibres once used cannot be recycled.
Which of the statements given above is/are correct?
- A1 onlyCorrect
- B2 only
- CBoth 1 and 2
- DNeither 1 nor 2
Explanation
Correct. Carbon fibres are widely used in automobile and aircraft components for their high strength-to-weight ratio. However, carbon fibre recycling technologies (pyrolysis, solvolysis) do exist, making statement 2 incorrect.
Why the other options are incorrect
- Option B
Carbon fibre recycling is technically feasible through methods like pyrolysis, so statement 2 is wrong.
- Option C
Statement 2 is incorrect because carbon fibres can be recycled, though the process is more complex than recycling metals.
- Option D
Statement 1 is correct; carbon fibre composites are standard materials in aerospace and automotive industries.
Q3Science·Chemistry in Everyday LifePYQ 2022
With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements:
1. Its fibres can be blended with wool and cotton fibres to reinforce their properties.
2. Containers made of it can be used to store any alcoholic beverage.
3. Bottles made of it can be recycled into other products.
4. Articles made of it can be easily disposed of by incineration without causing greenhouse gas emissions.
Which of the statements given above are correct?
- A1 and 3Correct
- B2 and 4
- C1 and 4
- D2 and 3
Explanation
Correct. PET fibres (polyester) are commonly blended with wool and cotton. PET bottles are among the most widely recycled plastics. However, PET is not suitable for storing all alcoholic beverages (especially spirits), and incineration of PET does produce CO₂.
Why the other options are incorrect
- Option B
PET containers are not recommended for storing high-proof alcoholic beverages, and burning PET releases CO₂, a greenhouse gas.
- Option C
Incineration of PET produces carbon dioxide and other emissions, making statement 4 incorrect.
- Option D
PET is not suitable for storing all types of alcoholic beverages, particularly spirits, as alcohol can leach chemicals from the plastic.
Q4Science·Chemistry in Everyday LifePYQ 2021
Water can dissolve more substances than any other liquid because:
- AIt is dipolar in natureCorrect
- BIt is a good conductor of heat
- CIt has high value of specific heat
- DIt is an oxide of hydrogen
Explanation
Correct. Water molecules are dipolar (have partial positive and negative charges), enabling them to surround and dissolve a wide range of ionic and polar substances, making water the 'universal solvent'.
Why the other options are incorrect
- Option B
Thermal conductivity determines how well a substance transfers heat, not its ability to dissolve other substances.
- Option C
High specific heat means water resists temperature changes, but this property does not explain its dissolving ability.
- Option D
Being an oxide of hydrogen is a chemical description of water but does not explain its exceptional solvent properties.
Q5Science·Chemistry in Everyday LifePYQ 2021
Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
- ALow-density polyethylene
- BPolycarbonateCorrect
- CPolyethylene terephthalate
- DPolyvinyl chloride
Explanation
Correct. BPA is a key monomer used in the manufacture of polycarbonate plastics, which are used in water bottles, food containers, and CDs.
Why the other options are incorrect
- Option A
LDPE is made by polymerising ethylene under high pressure and does not require BPA in its manufacture.
- Option C
PET is synthesised from ethylene glycol and terephthalic acid; BPA is not involved in its production.
- Option D
PVC is manufactured from vinyl chloride monomer and does not use BPA as a structural component.
Q6Science·Chemistry in Everyday LifePYQ 2019
In the context of which one of the following are the terms 'pyrolysis and plasma gasification' mentioned?
- AExtraction of rare earth elements
- BNatural gas extraction technologies
- CHydrogen fuel-based automobiles
- DWaste-to-energy technologiesCorrect
Explanation
Correct. Pyrolysis (thermal decomposition without oxygen) and plasma gasification (using ionised gas at extreme temperatures) are advanced waste-to-energy technologies that convert solid waste into syngas and other useful products.
Why the other options are incorrect
- Option A
Rare earth extraction uses chemical leaching and solvent extraction, not pyrolysis or plasma gasification.
- Option B
Natural gas extraction involves drilling, fracking, or conventional methods, not thermal decomposition processes.
- Option C
Hydrogen fuel cells power automobiles, but pyrolysis and plasma gasification are not primary methods for hydrogen vehicle technology.
Q7Science·Chemistry in Everyday LifePYQ 2017
Consider the following pairs:
Commonly used/consumed materials — Unwanted or controversial chemicals likely to be found in them
1. Lipstick — Lead
2. Soft drinks — Brominated vegetable oils
3. Chinese fast food — Monosodium glutamate
Which of the pairs given above is/are correctly matched?
- A1 only
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3Correct
Explanation
Correct. Studies have found trace amounts of lead in lipsticks, BVO has been used in some soft drinks as a flavour emulsifier, and MSG is a common flavour enhancer in Chinese fast food.
Why the other options are incorrect
- Option A
While lead in lipstick is correct, the other two pairs are also correctly matched.
- Option B
Lead traces in lipstick have been documented by multiple studies, so pair 1 is also correct.
- Option C
Brominated vegetable oils have been used as emulsifiers in certain soft drinks, so pair 2 is also correct.
Q8Science·Chemistry in Everyday LifePYQ 2015
With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements:
1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
3. Fuel cells produce electricity in the form of Alternating Current (AC).
Which of the statements given above is/are correct?
- A1 onlyCorrect
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Explanation
Correct. When pure hydrogen reacts with oxygen in a fuel cell, the only by-products are heat and water. Fuel cells can power devices of all sizes (not just buildings), and they produce DC, not AC.
Why the other options are incorrect
- Option B
Fuel cells produce Direct Current (DC), not AC, and they can power small devices like laptops, making both statements 2 and 3 wrong.
- Option C
Fuel cells inherently generate DC electricity through electrochemical reactions; an inverter is needed if AC is required.
- Option D
Statements 2 and 3 are both incorrect: fuel cells scale from portable devices to buildings, and they produce DC.
Q9Science·Chemistry in Everyday LifePYQ 2014
Which of the following is/are the example/examples of chemical change?
1. Crystallization of sodium chloride
2. Melting of ice
3. Souring of milk
Select the correct answer using the code given below.
- A1 and 2 only
- B3 onlyCorrect
- C1, 2 and 3
- DNone
Explanation
Correct. Souring of milk is a chemical change because lactose is converted into lactic acid by bacterial action, producing a new substance. Crystallization and melting are physical changes.
Why the other options are incorrect
- Option A
Crystallization and melting are physical changes because no new substance is formed; only the physical state changes.
- Option C
Crystallization of NaCl and melting of ice are physical changes as they involve only changes of state, not formation of new substances.
- Option D
Souring of milk involves a chemical reaction (fermentation), so at least one example is a chemical change.
Q10Science·Chemistry in Everyday LifePYQ 2013
Fruits stored in cold chambers exhibit long storage life because:
- AExposure to sunlight is prevented
- BConcentration of carbon dioxide in the environment is increased
- CRate of respiration is decreasedCorrect
- DThere is an increase in humidity
Explanation
Correct. Low temperatures in cold chambers slow down the rate of cellular respiration in fruits, reducing the production of ethylene and other ripening agents, thereby extending shelf life.
Why the other options are incorrect
- Option A
Preventing sunlight has a minor role; the primary factor is temperature-dependent metabolic activity.
- Option B
While controlled atmosphere storage may alter CO₂ levels, the cold chamber's main effect is reducing respiration rate through low temperature.
- Option D
Humidity control prevents drying but does not primarily account for extended storage life.
Q11Science·Chemistry in Everyday LifePYQ 2011
Aspartame is an artificial sweetener sold in the market. It consists of amino acids and provides calories like other amino acids. Yet, it is used as a low-calorie sweetening agent in food items. What is the basis of this use?
- AAspartame is as sweet as table sugar, but unlike table sugar, it is not readily oxidised in human body due to lack of requisite enzymes
- BWhen aspartame is used in food processing, the sweet taste remains, but it becomes resistant to oxidation
- CAspartame is as sweet as sugar, but after ingestion into the body, it is converted into metabolites that yield no calories
- DAspartame is several times sweeter than table sugar, hence food items made with small quantities of aspartame yield fewer calories on oxidationCorrect
Explanation
Correct. Aspartame is approximately 200 times sweeter than sucrose, so only tiny amounts are needed to achieve the same sweetness, resulting in negligible caloric intake.
Why the other options are incorrect
- Option A
Aspartame is metabolised normally in the body; the key is that far less of it is needed due to its intense sweetness.
- Option B
Aspartame does not become resistant to oxidation during food processing; it is actually heat-sensitive.
- Option C
Aspartame is metabolised into amino acids that do provide calories, but the quantity used is so small that the caloric contribution is negligible.
Q12Science·Chemistry in Everyday LifePYQ 2010
Excessive release of the pollutant carbon monoxide (CO) into the air may produce a condition in which oxygen supply in the human body decreases. What causes this condition?
- AWhen inhaled into the human body, CO is converted into CO₂
- BThe inhaled CO has much higher affinity for haemoglobin as compared to oxygenCorrect
- CThe inhaled CO destroys the chemical structure of haemoglobin
- DThe inhaled CO adversely affects the respiratory centre in the brain
Explanation
Correct. Carbon monoxide has about 200-250 times greater affinity for haemoglobin than oxygen, forming carboxyhaemoglobin and preventing oxygen transport.
Why the other options are incorrect
- Option A
CO is not readily converted to CO₂ inside the body; it binds directly to haemoglobin.
- Option C
CO does not destroy haemoglobin's structure; it occupies the oxygen-binding sites, blocking oxygen from attaching.
- Option D
While severe CO poisoning can affect brain function, the primary mechanism is competitive binding with haemoglobin, not direct action on the respiratory centre.