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Chemistry — UPSC Prelims Science & Environment previous year questions — page 2

79 solved previous year questions on Chemistry, papers from 1993 to 2023, drawn from UPSC CSE Prelims, UPPCS, UPSC CDS. Each carries the printed answer key and the explanation from the source compilation.

1. #41UPSC CDS 2022
   The atmosphere of Planet Venus is made up of thick and yellowish clouds of
   • AChl or ine
   • BSulphuric acid
   • CNitric acid
   • DBromine
   Answer: (B) Sulphuric acid
   Explanation

   Option b is the correct atmosphere of Planet Venus is primarily carbon dioxide (CO2) with traces of other thick and yellowish clouds in Venus' predominantly made up of sulphuric add Venus experiences extreme conditions, including a atmosphere and a runaway greenhouse effect, to the formation of sulphuric acid clouds. along with other aerosols, play a significant role climate and weather patterns. They reflect a of incoming sunlight back into space, Venus' highly reflective nature and its distinct Important Tips Venus's clouds contain toxic sulfur dioxide, and its surface temperature reaches A Venus year is equivalent to 225 Earth days, while a Venus day is equivalent to 243 Earth days. An afternoon on Venus is longer than a year. Venus is often referred to as the Morning or Evening Star. Venus has retrograde rotation, meaning the Sun rises in the west and sets in the east on Venus. Venus

2. #42UPSC CDS 2022
   Which one of the following is not an example of an oxidation reaction? 402. Which one of the following statements about biogas is not correct? dung in the absence of oxygen. residue. 403. Which one of the following is the main reason for acid rain? oxides in rain 404. Stinging hair of nettle leaves inject fluid in the human body causing burning pain. The fluid is 405. Milk of Magnesia is used when people suffer from indigestion of food. It is a 406. Which one of the following pairs of metals are very good conductors of heat? 407. School bells are made of metals because metals are 408. In the joining of railway tracks, iron oxide is made to react with 409. When water is heated from to its density original value. 410. Which one of the following statements about the process of photosynthesis is correct? kinetic energy which oxidizes carbon dioxide. chemical energy which causes reduction. of water. of light which causes oxidation of carbon dioxide causes splitting of water molecules and reduction of carbon dioxide. 411. Kwashiorkor, a form of malnutrition, is caused by the deficiency of 412. Which one of the following pairs of enzymes do not work at acidic pH? 413. Urea is produced by metabolism of 414. Deficiency of iron causes 415. A patient's abdomen (alimentary canal) can be examined by X-ray after administering which one of the following metal salts in the patient's meal? 416. Cell wall is not present in cells of 417. A child receives a tall, beautiful plant as a birthday gift from his father with a quiz. The father asked her how she would verify whether this tall plant was the progeny of both the tall parents or one tall and one short parent plant. She could verify this through 418. A student was doing an experiment on increasing the cell division among plants. She asked her supervisor to suggest the specific plant hormone for the same. Had you been her supervisor, which plant hormone would you suggest? 419. Which cell have their own DNA and Ribosomes? 420. An antibiotic is not useful against a virus whereas a vaccine is. Which one of the following is the most appropriate reason for this? whereas virus has DNA. chemical nature, whereas a vaccine is a protein which works well to kill a virus. material of a virus. pathways which can be blocked by an antibiotic. But a vaccine can boost an immune system to fight the virus. 421. 'Sleeping sickness' is caused by 422. Rupa and Sachin observed an animal in their school garden. Rupa called it an insect while Sachin identified it as an earthworm. Which one of the following characteristics confirms that it is an segmentation. symmetrical. 423. Which of the following limits the number of trophic levels in a food chain? trophic levels 424. Which one of the following statements about variations is not true? reproduction. chances of survival. variation. factors. 425. While studying vegetation of an area, terms like 'population' and 'community' are often used. Which one of the following statements best describes a population? living in the same area at the same time. living in different areas during different seasons. components. species, living in the same area at the same time. 426. In the human body, blood flows through a process of double circulation. Which one of the following statements is true in this regard? the heart from the lungs. in oxygen and is brought to the right side of the heart. of the heart is brought to the lungs for oxygenation. the heart is sent around the body. 427. In which of the following groups of organisms, is food material broken down outside the body and absorbed? 428. Which of the following statements about 'fission' is correct?
   • AThe taste of butter changes if left for a longer period
   • BA white substance is formed when an aqueous solution of barium chl or ide is mixed with sodium sulphate solution
   • CA reddish-brown powder gets coated on articles made of iron
   • DWine gets sour with time 401. While burning hydrocarbon fuels, if we see a yellow flame with lots of black smoke, it means that the fuel is
   Answer: (B) A white substance is formed when an aqueous solution of barium chl or ide is mixed with sodium sulphate solution
   Explanation

   Option b is the correct white substance is formed when an aqueous solution chloride is mixed with sodium sulphate solution reaction does not involve oxidation. It is a where the formation of a white precipitate to the combination of barium chloride and a is incorrect: The taste of butter changes if left longer period - This is an example of oxidation as the butter undergo oxidation over time, resulting in a c is incorrect: A reddish-brown powder gets articles made of iron - This is an example of oxidation reacts with oxygen in the presence of moisture to which appears as a reddish-brown d is incorrect: Wine gets sour with time - This example of oxidation as the ethanol in wine reacts in the air to form acetic acid, leading to the sour Solution: Option b is the correct yellow flame with lots of black smoke combustion. In this case, the fuel is likely unsaturated hydrocarbons. Unsaturated

3. #43Previous year
   With reference to Agni-IV Missile, which of the following statements is/are correct? [UPSC CSE Pre 2014) 1. It is a surface-to-surface missile. 2. It is fueled by liquid propellant only. 3. It can deliver one-tonne nuclear warheads about km away.Select the correct answer using the code given below
   • A1 only
   • B2 and 3 only
   • C1 and 3 only
   • D1, 2 and 3
   Answer: (A) 1 only
   Explanation

   Option a is the correct l is correct- The Agni-IV is a with a range of over 4,000 2 is incorrect- The Agni-IV is a two-stage, solid fueled 3 is incorrect- The Agni-IV has a of over 4,000 km, and it can carry a payload of up kg Important Tips A brief comparison between Solid Propellant and Liquid Propellant: Feature Solid propellant Liquid propellant State Solid Liquid Composition Oxidizer and fuel are mixed together in a solid Oxidizer and fuel are stored separately and mixed matrix. before combustion. Combustion Burns at a constant rate, determined by the shape Combustion can be controlled by varying the flow and dimensions of the propellant grain. rate of the oxidizer and fuel. Thrust Provides a high initial thrust but thrust decreases Can provide a constant thrust level throughout over time as the propellant is consumed. the burn. Complexity Simpler to manufacture and store than liqui

4. #44UPSC CSE Prelims 2011
   A company marketing food product advertises that its items do not contain trans-fats. What does this campaign signify to the customers? 1. The food products are not made out of hydrogenated oils. 2. The food products are not made out of animal fats/oils. 3. The oils used are not likely to damage the cardiovascular health of the consumers.Which of the statements given above is/are correct?
   • A1 only
   • B2 and 3 only
   • C1 and 3 only
   • D1, 2 and 3
   Answer: (C) 1 and 3 only
   Explanation

   Option c is the correct fatty acids (TFAs) or Trans fats are the most of fats which can have much more adverse effects on than a'ny other dietary TFAs are formed when hydrogen is made to the oil to produce fats resembling pure ghee/butter. diet the major sources of artificial TFAs are the vegetable oils the natural TFAs are present in meats and though in small amounts

5. #45UPSC CSE Prelims 2008
   Consider the following statements in respect of a jet engine and a rocket: 1. A jet engine uses the surrounding air for its oxygen supply and so is unsuitable for motion in space. 2. A rocket carries its own supply of oxygen in the form of gas and fuel.Which of the statements given above is/are correct?
   • A1 only
   • B2 only
   • CBoth 1 and 2
   • DNeither 1 nor 2
   Answer: (A) 1 only
   Explanation

   Option a is the correct l is correct: Jet engines, whether turbojet rely on the intake of air from the for their combustion process. They air, mix it with fuel, ignite it, and expel it at high generate thrust. In the vacuum of space, there is no intake, making jet engines unsuitable for propulsion 2 is incorrect: Rockets do carry their own fuel, which includes both a fuel source and an the oxidizer used in rockets is typically in of a chemical compound, such as liquid oxygen than gaseous oxygen. Rockets combine their oxidizer internally and do not rely on the for combustion, which allows them to operate vacuum of space. Important Tips Jet Engine vs Rocket: Characteristic Jet Engine Rocket Engine Type of engine Air-breathing Non-air breathing Propulsion Thrust generated Thrust generated system by pushing air by expelling backwards propellant backwards Fuel Jet fuel Rocket fuel Efficiency

6. #46UPSC CSE Prelims 1996
   Physico-chemical characteristics of water in water sources undergo changes due to
   • AAquatic macrophytes
   • BAquatic fungi
   • CEffluents
   • DEvapotranspiration
   Answer: (C) Effluents
   Explanation

   Option c is the correct originating from residential, industrial, sources, encompass diverse pollutants, substances, nutrients, and toxic compounds. into water bodies, these effluents can the physical and chemical properties of the instance, they can elevate the organic matter in increased Biological Oxygen Demand diminished oxygen levels. Additionally, effluents nutrient levels, fostering the development of which, in turn, deplete oxygen levels, posing to aquatic life like fish. Furthermore, effluents toxic chemicals with adverse impacts on both and human health. Important Tips What is Algal Bloom? An algal bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. Algal blooms can be green, blue-green, red, or brown, depending on the type of algae. Algal

7. #47UPSC CSE Prelims 2021
   In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?
   • ACarbon cycle
   • BNitrogen cycle
   • CPhosphorus cycle
   • DSulphur cycle
   Answer: (C) Phosphorus cycle
   Explanation

   Option c is the correct and Nitrogen cycle are the gaseous cycles. In the main reservoir of nutrient is the atmosphere hydrosphere. In sulphur cycle, nutrient is released of rocks, erosional runoff and decomposition matter. The sulphur cycle is mostly sedimentary of its compounds hydrogen sulphide and (SO2) add a gaseous component to its Phosphorus cycle, nutrients got released mainly of rocks since the Phosphorus mainly occurs as in phosphate rocks. It enters the cycle from mining activities

8. #48UPSC CSE Prelims 2018
   Which of the following leaf modifications in the desert areas to inhibit water loss? 1. Hard and waxy leaves 2. Tiny leaves 3. Thorns instead of leavesSelect the correct answer using the codes given below
   • A2 and 3 only
   • B2 only
   • C3 only
   • D1, 2 and 3
   Answer: (D) 1, 2 and 3
   Explanation

   Option d is the correct 1 is correct. Desert plants are adapted to environment in many different plants have hard and waxy leaves to reduce the water through transpiration. The waxy covering on young stems, and fruit is called the "cuticle". It of cutin, a wax-like material produced by that is chemically a hydroxy fatty acid. The this covering is to help the plant retain water. In that is very 2 is correct. Small leaves on desert plants reduce moisture loss during transpiration. Small less evaporative surface per leaf. In addition, a in the sun doesn't reach as high a temperature as leaf in the 3 is correct. In arid regions, some plants instead of leaves to avoid loss of water transpiration. Desert plants have few or no leaves, foliage is either waxy, leathery, hairy or needle shaped water loss through transpiration. Some of them leafless, with pricks or desert plants grow leaves during

9. #49UPPCS 2021
   The cycling of elements in an ecosystem is called
   • AChemical cycles
   • BBiogeochemical cycles
   • CGeological cycles
   • DGeochemical cycles
   Answer: (B) Biogeochemical cycles
   Explanation

   Option b is the correct cycles are the pathways by which and compounds move through the geosphere, and hydrosphere. These essential for life on Earth, as they provide the other resources that organisms need to survive Important Tips Types of Biogeochemical cycles: The water cycle is the movement of water through the atmosphere, hydrosphere, lithosphere, and biosphere. Water is essential for life, and it is used by organisms for drinking, bathing, and regulating their body temperature. The carbon cycle is the movement of carbon through the atmosphere, biosphere, and geosphere. Carbon is an essential element for life, and it is used by organisms to build their bodies and produce energy. The nitrogen cycle is the movement of nitrogen through the atmosphere, biosphere, and geosphere. Nitrogen is an essential element for life, and it is used by organisms to build their bodies and produce prot

10. #50UPPCS 2012
    Which of the following does NOT add carbon dioxide to the carbon cycle on the planet Earth?
    • ARespiration
    • BPhotosynthesis
    • CDecay of organic matter
    • DVolcanic action
    Answer: (B) Photosynthesis
    Explanation

    Option b is the correct is the process by which plants use and carbon dioxide to create oxygen and energy form of glucose. On the other hand, Respiration, Organic Matter, and volcanic action, all contribute to Dioxide addition to the atmosphere. animals and plants results in the release of contributing to atmospheric levels of this the decay of organic matter, including animals, leads to the release of carbon dioxide into Additionally, volcanic eruptions also play in introducing carbon dioxide and other gases into Important Tips Various factors influence the process of photosynthesis: Light Intensity: A higher light intensity accelerates photosynthesis, whereas lower light levels reduce the rate of photosynthesis. CO2 Concentration: Photosynthesis rates increase with higher carbon dioxide (CO2) concentrations. Typically, a range of 300 to 400 parts per million (PPM) of CO2 is suitable fo

11. #51UPSC CSE Prelims 2014
    There is some concern regarding the nanopartides of some chemical elements that are used by the industry in the manufacture of various products. Why? 1. They can accumulate in the environment and contaminate water and soil. 2. They can enter the food chains. 3. They can trigger the production of free radicals.Select the correct answer using the code given below
    • A1 and 2 only
    • B3 only
    • C1 and 3 only
    • D1, 2 and 3
    Answer: (A) 1 and 2 only
    Explanation

    Option a is the correct terephthalate (or PET) is the most polymer resin of the polyester family and in fibers for clothing, containers for liquids and thermoforming for manufacturing. PET is and has the digit 1 as its resin identification Statement 1 is correct: PET fibers can be blended and cotton fibers to reinforce their properties. Terylene is a trademark name for a polyester is made from PET and blended with cotton or 2 is incorrect: Containers made of PET used to store any alcoholic beverage, as PET is to ethanol and can degrade over time. PET mainly used for water, soft drinks, juices, and edible 3 is correct: Bottles made of PET can be other products, such as fibres, carpets, and engineering plastics. PET recycling is a well established industry that reduces waste and saves energy 4 is incorrect: Articles made of PET easily disposed of by incineration without gas emissions, as P

12. #52UPPCS 2016
    Which of the following is/are used as a disinfectant of water?
    • AOzone
    • BChl or ine dioxide
    • CChloramine
    • DAll of the above
    Answer: (D) All of the above
    Explanation

    Option d is the correct Naess, a Norwegian philosopher, coined the ecology" in 1973. Naess used the term to describe environmental philosophy that emphasized the of all living things and the need for humans to live with nature. Important Tips Deep ecology is founded on several fundamental principles, which include: All forms of life possess intrinsic value and are not merely commodities for human exploitation. Humans are not isolated from the natural world but are integral components of a broader, interconnected web of life. The diversity of human cultures and societies is significant and deserves reverence. Human intervention in the natural world should be kept to a minimum

13. #53UPPCS 2009
    Which of the following gases is commonly used in Cryo-Bank for ex-situ conservation?
    • ANitrogen
    • BOxygen
    • CCarbon dioxide
    • DMethane
    Answer: (A) Nitrogen
    Explanation

    Option a is the correct nitrogen is commonly used in cryobanks for Liquid nitrogen has a boiling point of Celsius, which is well below the freezing point This makes it ideal for storing biological samples low temperatures, which prevents them from decaying

14. #54Previous year
    Which of the following forests is known as the 'lungs of the planet earth'? [R.A.S./R.T.S. (Pre) 2013
    • ARainforests of North-East India
    • BTaiga forest
    • CTundra forest
    • DAmazon rain forest
    Answer: (D) Amazon rain forest
    Explanation

    Option d is the correct Tropical rainforest of Amazon is known as of planet earth because they are responsible production of about of the earth's oxygen. a large amount of carbon dioxide from the air out oxygen, making them a vital contributor to oxygen balance and overall ecosystem health

15. #55UPSC CSE Prelims 2012
    The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs
    • AThe water vapour of the air and retains its heat
    • BThe ultraviolet part of the solar radiation
    • CAll the solar radiations
    • DThe infrared part of the solar radiation
    Answer: (D) The infrared part of the solar radiation
    Explanation

    Option d is the correct of crop residue is a serious problem, especially northern part of India causing widespread air the National Capital of these residues emit gases like sulphur oxides of nitrogen carbon dioxide monoxide (CO), black carbon (BC), (OC), methane (CH4), volatile organic non-methane hydrocarbons (NMHCs), and aerosols etc

16. #56Practice set
    Which of the following are the potential applications of Ultrasound Waves? l. To detect flaws and cracks in metal blocks. 2. To diagnose heart conditions. 3. To break the stones formed in the kidney. 4. To measure the distance, direction and speed of underwater objects.Select the correct answer using the code given below
    • A1 and 4 only
    • B1, 2 and 4 only
    • C2 and 3 only
    • D1, 2, 3 and 4
    Answer: (D) 1, 2, 3 and 4
    Explanation

    Option d is the correct are high frequency waves and they are travel along well-defined paths even in the presence Ultrasounds are used extensively in industries medical 1 is correct: Ultrasounds can be used to and flaws in metal blocks. Metallic generally used in construction sectors. The cracks inside the metal blocks are invisible from outside waves are allowed to pass through the and if there is even a small defect, the waves back indicating the presence of the flaw or 2 is correct: Ultrasonic waves are made to various parts of the heart and form the image of This technique is called echocardiography, a type imaging of the heart, using standard can be useful in diagnosing heart 3 is correct: Ultrasound may be employed to stones formed in the kidneys into fine grains. later get flushed out with 4 is correct: Sound Navigation And is a device that uses ultrasonic waves to distance, dire

17. #57Practice set
    Which of the following is a reason why aluminium is used for wrapping food items?
    • AAluminium usually does not react with acid particles contained in the food
    • BPoor heat conductivity of aluminium keeps the food inside aluminium wrap warm
    • CAluminium is incapable to react with water content of the food inside the wrap
    • DIt is possible to make a thin sheet out of aluminium metal owing to its malleable property
    Answer: (D) It is possible to make a thin sheet out of aluminium metal owing to its malleable property
    Explanation

    Option d is the correct a is incorrect: Non metals generally do not acids but metals (including Aluminium) react and produce hydrogen gas. Thus Aluminum does with acid content of the food is not b is incorrect: Aluminium is the good conductor thus aluminium is being used as food wraps owing poor thermal conductivity is not c is incorrect: Aluminium.will react readily or air to produce aluminium oxide,'thus to react with water content in food is not the produced Aluminium Oxide is not reactive it best property for using aluminium as food d is correct: The property of metals by which be beaten into thin sheets is called malleability. such as Iron, Silver and Aluminium show and non-metals such as coal and pencil lead do this property. This property is one of the major Aluminium is used to wrap the food items

18. #58Practice set
    Which one of the following statements best describes the reason behind of Sodium in the kerosene oil?
    • AIt reduces the melting point of the Sodium
    • BIt leads to electroplating on Sodium
    • CSodium is a highly reactive metal
    • DIt increases the weight of the Sodium
    Answer: (A) It reduces the melting point of the Sodium
    Explanation

    Option a is the correct a is correct: Curd is obtained from milk through a process called curdling. Lactic acid. When lactic acid in the curd the metals like Brass and Copper, it causes the creation of products that cannot be digested by and d are incorrect: Tartaric Acid is acid found in Tamarind and grapes. Ascorbic an antioxidant agent that functions in fighting in detoxifying reactions, and in the formation in fibrous tissues. It is found in citrus fruits. is also known as ethanoic acid. Acetic acid is a of fermentation and gives vinegar its Solution: Option b is the correct metals are a group of elements that are located on sid.e of the periodic table, typically to the right of 1 is incorrect: Some non-metals, such as phosphorus, can react with oxygen to form acidic means th_at these oxides will have acidic dissolved in water. However, not all non-metals with oxygen form acidic oxid

19. #59Practice set
    With reference to 'Non-Metals', consider the following statements:L The reaction of non-metals with oxygen gives only acidic oxides. 2. Most non-metals do not react with water under normal conditions. 3. All the existing non-metals do not react with acid. 4. Non-metals react with base to form salt and water.How many of the statements given above are correct?
    • AOnly one
    • BOnly two
    • COnly three
    • DAU four
    Answer: (C) Only three
    Explanation

    Option c is the correct 1 and 2 are correct: Hard water high rate of mineral content, which is formed penetrates through deposits of limestone and water contains a large percentage of calcium carbonates and this is what makes the One of the most common indicators of hard water lack of lather when water is used with 3 is Water hardness is a big an effective solution is using a water softener, remove calcium from the water. There are softeners available in the market and they are ion exchange systems. In such systems, hardness exchanged for salt (sodium or potassium) ions. is done within the resin tank of the water resin beads are covered with salt ions. In the process, the water flows through the resin the hard water reacts with salt ions, which of sodium ions. This results in removal of water

20. #60Practice set
    With reference to different acids present in food, consider. the following pairs: 1. Milk Lactic Acid 2. Amla Oxalic Acid 3. Grapes Tartaric Acid 4. Spinach Ascorbic acidHow many of the pairs given above are correctly matched?
    • AOnly one
    • BOnly two
    • COnly three
    • DAll four
    Answer: (A) Only one
    Explanation

    Option a is the correct Assertion and Reason are correct and Reason is explanation of is correct: The sting of an ant contains which is a type of acid found in many ants. When bites, it injects this acidic liquid into the skin, cause mild to moderate pain, itching, and redness at of the bite. The severity of the symptoms depends on of ant and the person's sensitivity to the effect of the sting can be neutralized by rubbing soda (sodium hydrogen carbonate) or which contains zinc carbonate. Baking soda can with a small amount of water to create a paste applied to the bite. It can help to alleviate symptoms ant bite such as itching and pain by creating a neutral and reducing the acidity of the is correct: Baking soda (sodium bicarbonate) is alkali that can help to neutralize acids. It can help symptoms of an ant bite such as itching and pain a neutral pH environment and reducing the soda ha

21. #61Practice set
    Graphene is said to be a disruptive technology; one that could open up new markets and even replace existing technologies or materials. Which of the following can be the potential applications of Graphene? 1. As carriers of drugs and antigens in the human body. 2. Can be used to enhance the strength of other materials. 3. Making heat-spreading solutions, such as heat sinks or heat dissipation films. 4. In batteries and supercapacitors to store more energy and charge faster. 5. In anti-corrosion coatings and paints.Select the correct using the code given below: independently. known as a polyatomic ion. identity in chemical reactions. are reactive
    • A1, 2,3 and 5 only
    • B2, 3, 4 and 5 only
    • C1, 2, 3 and 4 only
    • D1, 2, 3, 4 and 5
    Answer: (C) 1, 2, 3 and 4 only
    Explanation

    Option c is the correct answer. Statement a is correct. Most of the atoms do. not exist independently but, the atoms of noble gases which are highly in ert can exist independently. For example, Helium (He), Neon (Neon) and Argon (Ar). Statement b is correct. Compounds composed of metals and nonmetals contain charged species. The charged species are known as ions. An ion is a charged particle and can be negatively or positively charged. A negatively charged ion is called an 'anion' and the positively charged ion, a 'cation'. A gro.up of atoms carrying a charge is known as a polyatomic ion. Statement c is incorrect. As per Daltons atomic theory atoms are indestructible and retain their identity in all chemical reactions. This is basically the Law of Conservation of Matter, stating that an equal amount of mass exists before and after a reaction. Statement dis correct. Atoms which have imbal

22. #62Practice set
    When a piece of wood is burnt, it releases a combination of oxygen, smoke, ashes, water vapor and other gases. Burning of wood is an example of
    • AArchimedes principle
    • BLaw of Conservation of Momentum
    • CLaw of Conservation of Mass
    • DBernoulli's principle
    Answer: (C) Law of Conservation of Mass
    Explanation

    Option c is the correct atomic number of an atom is defined as the protons present in the nucleus of an mass number of an atom is defined as the total and neutrons present in the nucleus of an 1 is correct and 2 is correct. Isotopes are the atoms of the same element, having the same but different mass numbers. There are of hydrogen atom, namely protium, deuterium The chemical properties of isotopes are similar physical properties are are different forms of the. same element. due to the different bonding of the atoms arranged in sequence, thus forming a new structure. have the same element. So, the proton and are the same and so the atomic mass is also 3 is correct. Allotropes of Carbon are graphite. They are formed by carbon atoms but lies in the manner in which the carbon bonded to one another. In diamond, each carbon bonded to four other carbon atoms forming a rigid three dimensional s

23. #63Practice set
    With reference to reaction of metals with different medium, which of following statements is/are correct? 1. Metals on reaction with oxygen produces Metal Oxides. 2. All Metals react with water to produce hydrogen.Select the correct answer using the code given below
    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Answer: (C) Both 1 and 2
    Explanation

    Option c is the correct is a diatomic gas that is colorless, odorless is insoluble in a is lncorrect. The regular air has tendency out of microscopic pores in the tires, this will cause inflation pressure. When air gets pressurized, in it turns into a liquid. When this air is your tire, this liquid will come with it as well. are driving, your fire will heat up which will turn into a gas. This makes it expand which increases b is incorrect. The Volumetric energy to the amount of energy that can be contained given Increasing the volumetric energy batteries allows electric vehicles (EVs) to travel increasing the size of the battery c is correct Nitrogen is drier in oxygen content) than compressed air which not regulate the tyre pressure and temperature on and extremely long drives but also causes damage and corrosion of the metal tyre rims. air has more water and oxygen which with the chang

24. #64Practice set
    With reference to the excretory system in plants, consider the following statements: 1. Like humans, plants have a specialised system for excretion. 2. Many plant secretions like rubber, gums and resins are actually waste products.Which of the statements given above is/ are correct?
    • A1 only
    • B2 only
    • CBoth 1 and 2
    • DNeither 1 nor 2
    Answer: (B) 2 only
    Explanation

    Option b is the correct 1 is incorrect: A strong pigment named carotenoids) is responsible for the bright red application of henna. Henna/ Mehendi is a form of widely prevalent in South Asia, Middle East The flowering plant from which henna is derived Lawsonia inermis. The leaves of henna when not stain the skin. They will stain only after the lawsone molecules (2-hydroxy-l, in the leaves, after smashing them with acidic liquid like 2 is correct: The unique smell that each type of flower (called the floral scent/ due to low weight Volatile Organic Compounds are created and emitted by floral tissues in the The smell is a result of a complex combination of organic compounds. Its main purpose is herbivores and attract pollinators. Important Tips Carotenoids are a type of phytonutrient (plant pigments) that give the characteristic red, orange and yellow colour seen in many fruits and vegetab

25. #65Practice set
    Which of the following organisms practice anaerobic respiration? 1. Yeast 2. Earthworms 3. Clostridium 4. Button Mushrooms 5. Methanogenic ArchaeaSelect the correct option using the code given below
    • A1, 2 and 3 only
    • B2, 3 and 4 only
    • C1, 3 and 5 only
    • D1, 2, 3, 4 and 5
    Answer: (D) 1, 2, 3, 4 and 5
    Explanation

    Option d is the correct is the process by which living organisms into energy for carrying out life processes. Respiration two kinds - aerobic (using oxygen) and anaerobic Anaerobic cellular respiration creates lactic acid body as a Acid is the acid produced in the body as a result cellular respiration. The accumulation of near the muscles carrying out the anaerobic fatigue and results in a cramp. 1 Important Tips Acetic Acid is not found naturally in the human body. It is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. It is one of the simplest carboxylic acids and has the chemical formula In nature, Acetic acid is produced and excreted by acetic acid bacteria, notably the genus Acetobacter and Clostridium acetobutylicum. These bacteria are found universally in foodstuffs, water, and soil, and acetic acid is produced naturally as fruits a

26. #66Practice set
    "It is an umbrella term for any technology that alters reality by adding digital elements to the physical or real-world environment to an extent. It includes any existing or new technologies that may be created in the future that alter reality, either by blending the digital and the physical world or by creating a fully virtual environment." Which of the following options has been described in the above passage?
    • AAugmented Reality
    • BMixed Reality
    • CExtended Reality
    • DVirtual Reality
    Answer: (C) Extended Reality
    Explanation

    Option c is the correct reality (XR) is an umbrella term for that alters reality by adding digital the physical or real-world environment to any includes, but is not limited to, augmented reality reality (MR) and virtual reality (VR). It existing or new technologies that may be created in that alter reality, either by blending the digital physical world or by creating a fully virtual environment. Important Tips In augmented reality, virtual information and objects are overlaid on the real world. This means users are not isolated from the real world and can still interact and see what's going on in front of them. The most well known examples of AR are the Snapchat filters that put digital objects such as hats or glasses onto your head. Mixed reality is a seamless integration of the real world and rendered graphics, which creates an environment in which users can directly interact with the

27. #67Practice set
    With reference to nutrient consider the following: 1. The nutrient cycling in an entire ecosystem is known as biogeochemical cycle. 2. Phosphorous circulates mainly by the means of a gaseous cycle. 72. 3. Hydrologic cycle is driven by solar energy.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (B) Only two
    Explanation

    Option bis the correct I is correch Elements or mineral nutrients in circulation moving from non-living to living back to the non-living components of the a more or less circular fashion. This circulation in is known as biogeochemical 2 is incorrect: Phosphorus, calcium circulate by means of the The element involved in the sedimentary follows a basic pattern of flow through mountain building, volcanic activity transport through the excreta of marine 3 is correct: The hydrologic cycle is the water in the Earth-atmosphere system driven by solar energy. Water moves from one another by the of evaporation, precipitation, deposition, runoff, groundwater flow

28. #68Practice set
    Which of the following statements is/are correct about Sulphur cycle? 1. It is a sedimentary cycle as it does not involve gaseous component. 2. Sulphur is taken by plants in the form of sulphates.Select the correct answer using the code given below
    • A1 only
    • B2 only
    • CBoth 1 and 2 73
    • DNeither 1 nor 2
    Answer: (B) 2 only
    Explanation

    Option bis the correct I is incorrect. Although Sulphur cycle is it involves gaseous components like and Sulphur dioxide. Organisms like marshes, release Sulphur in the form of Hydrogen gaseous component) by anaerobic respiration. volcanic eruption, fossil fuels release large amount dioxide (a gaseous component) in the Practkebook 2 is correct whatever Sulphur by the plant in the form of sulphate through. a series of metabolic. processe. amino aci.d which is of autotrnph tissue.s. It.then food chain

29. #69Practice set
    Consider the following pairs: 1. Fragmentation Detritivores break down detritus into smaller particles. 2. Humification Degradation of the humus and release of inorganic nutrients. 3. Mineralisation Accumulation of organic matter into a substance fllfHow many of the above pairs are correctly matched?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (A) Only one
    Explanation

    Option a is the correct break down complex organic matter i inorganic substances like carbon dioxide, water and the process is called decomposition. The in the process of decomposition are catabolism, humification and mineralisation. Pair I is correct. Fragmentation is the process of of detritus into smaller particles by the detritivores. 2 is incorrect. The process of degradation of some microbes and release of inorganic nutrients the process known as mineralisation. On the Humification is the process of accumulation of coloured amorphous substance called humus that resistant to microbial activity. Humification occur during decomposition in the 3 is incorrect. Accumulation of organic matter into is process of humification (not humus is humus is degraded by some microbes and inorganic nutrients occurs by the process known Bacterial and fungal enzymes into simpler inorganic substances. Th

30. #70Practice set
    Which among the following is/are the applications of seaweeds? 1. It acts as a bioindicator. 2. Helps in removal of heavy metals from marine ecosystem. 3. Production of bioethandl 4. Preparing toothpaste and cosmetics.Which of the statements given above is/are correct?
    • A1 only
    • B2 and 3 only
    • C1, 2 and 3 only
    • D1, 2, 3 and 4
    Answer: (D) 1, 2, 3 and 4
    Explanation

    Option dis the correct 1 and 2 are correct: Seaweeds absorbs including the heavy metals from the So, if there is imbalanced amount of nutrients water, it also gets reflected in the seaweeds. as an indicator of the health of the marine green seaweed Ulva rigida can act as a metals (Zn, Cu, Pb and Cd) in a low-salinity 3 is correct: Seaweed is highly suitable Between 85 and of seaweed is water, seaweed is very suitable for biofuel-making anaerobic digestion to make biogas and fermentation ethanol. In addition, many seaweed species, like have high carbohydrate and low lignin content that for making 4 is correct: Seaweed is also used as an preparing toothpaste, cosmetics and paints

31. #71Practice set
    Which of the following can be found as pollutants in the drinking water in some parts of India? 1. Arsenic 2. Sorbitol 3. Fluoride 4. Formaldehyde 5. UraniumSelect the correct answer using the codes given below
    • A1 and 3 only
    • B2, 4 and 5 only
    • C1, 3 and 5 only
    • D1, 2, 3, 4 and 5
    Answer: (C) 1, 3 and 5 only
    Explanation

    Option c is the correct by the Central Water Commission show (surface drinking water sources) in India are toxic heavy metals such as lead, arsenic, and Fluride mercury and nickel. Important Tips Sobitol and Formaldehyde are not drinking water pollutants. Sorbitol is a type of carbohydrate called a sugar alcohol. It contains about one-third fewer calories than sugar and is 60 percent as sweet and occurs naturally in a variety of berries and fruits. Formaldehyde is a simple chemical compound made of hydrogen, oxygen and carbon. All life forms - bacteria, plants, fish, animals and humans - naturally produce formaldehyde as part of cell metabolism

32. #72Practice set
    Which of the following statement is/are incorrect about acid rain? 1. Its impact on food crops is minimized by the use of fertilizers. 2. Most of the acid particles in the atmosphere falls back to earth as wet deposition. 3. They make some conifers less cold tolerant and even lead to their death. 4. Indian soils are heavily impacted by acid rain due to its tropical location.Select the correct answer using the code given below
    • A1 and 2 only
    • B1 and 3 only
    • C2 and 3 ortly
    • D2 and 4 only
    Answer: (D) 2 and 4 only
    Explanation

    Option d is the correct 1 is correct: Acid rain damages plants as away nutrients with it. But in case of food is application of lime and fertilizers which impact of acid rain by supplementing extra 2 is incorrect: Wet deposition in wet weather where acidity comes down in rain, snow, fog, etc. But dry depositions accounts for acidity which falls back on earth. It usually occurs weather and while falling down sticks to the vegetation, car, 3 is correct: Acid rain leads to washing As upland and mountainous areas are to acid rain, its effect on conifers is also calcium is leached from the needles of red trees become less cold tolerant and exhibit and even 4 is incorrect: Indian soils are mostly has a good buffering ability, which makes them to harmful impacts of acid rain

33. #73Practice set
    "These are a result of symbiotic association between fungi and plant roots. They are even considered as means for restoration and remediation of polluted environments because of its ability to accumulate heavy metals and radionuclide. Further they serve as an important source of food for certain invertebrate and vertebrate animals:' The above paragraph best indicates which of the following organisms?
    • ALichens
    • BMycorrhizae
    • CPneumatophores
    • DUlva fasciata
    Answer: (B) Mycorrhizae
    Explanation

    Option b is the correct are a symbiotic association between and fungi. The fungi colonise the root system of a providing increased water and nutrient while the plant provides the fungus formed from is believed as a means for restoration and remediation environments because of its ability to metals and radionuclide. Further they serve important source of food for both invertebrate animals. Important Tips Lichens are a result of symbiotic association between algae and fungi. Lichens serve as a good indicator of air pollution as they are sensitive to Sulphur Dioxide. Mangroves produce pneu.matophores (blind roots/ aerial roots) to overcome respiration problems in anaerobic soil conditions or adventitious roots i.e, roots emerging from main trunk of the Ulva fasciata, also known as sea lettuce, is a common green alga that is used for consumption in many parts of the world. Ulva fasciata has

34. #74Practice set
    With reference to the Nilambur Teak, sometimes seen in the consider the following statements: 1. It is the first forest produce to get a GI tag in India. 2. Nilambur teak is famous for its large size and durability. 3. It exhibits high resistance to fungal decay.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (C) All three
    Explanation

    Option c is the correct l is correct. Nilambur teak is grown in of Kerala. It is also known as Malabar teak and of Teak. It was accorded Geographical Indication by the Geographical Indication (GI) Registry in 2017. the first forest produce to get GI 2 is correct. Nilambur teak is famous for its superior colour and durability. Its durability is the synergistic effect of total extensive 3 is correct. They are highly resistive to The hydrophobicity, anti-oxidant properties and are due to a caoutchouc compound. The teak is extremely resistant to attack of insects and fungi. Important Tips Nilambur forests and teak plantations are the major sources of quality teak wood in India. It is au important timber tree in India and known worldwide for its unique quality for shipbuilding and yacht manufacturing. Nilambur teak is internationally known for its superior quality and elegant appearance

35. #75Practice set
    With reference to Ocean acidification, consider the following statements: 1. The concentration of hydrogen ions in the ocean increases. 2. The pH of ocean increases, and the oceans become more alkaline. 35. 3. The process of eutrophication leads to ocean acidification.How many of the above statements are correct?
    • AOnly one
    • BOnly two
    • CAll three
    • DNone
    Answer: (B) Only two
    Explanation

    Option b is the correct 1 is correct. In the ocean acidification, the atmospheric carbon dioxide by the ocean increases, in increase in concentration of hydrogen ions in 2 is incorrect. As the concentration of in the ocean increases, the concentration of decreases. This leads to decrease in the pH of the the oceans become less 3 is correct. The eutrophication of coastal to large plankton blooms, and when these and sink to the sea bed the subsequent bacteria decomposing the algae leads to a decrease in oxygen and an increase in CO2. This leads to ocean pH

36. #76Full-length test
    Which of the following metals can be extracted from the e-waste produced by mobile phones? 1. Palladium 2. Silver 3. Gold 4. Copper 5. NeonSelect the correct answer using the code given below
    • A1, 3 and 4 only
    • B2, 3 and 5 only
    • C1, 2, 3 and 4 only
    • D1, 2, 3, 4 and 5
    Answer: (C) 1, 2, 3 and 4 only
    Explanation

    Option c is the correct phones have precious metals such as gold, palladium; special metals such as cobalt, indium and metals such as copper and are present in individual phones in traces, but of mobile phones has as much as 340 grams of kilograms of silver, 140 grams of palladium and of copper, states a 2009 report on e-waste by Nations Environment Programme is a noble gas. Its colour is reddish-orange and in a vacuum discharge tube and in neon lamps. It present in mobile phones

37. #77Full-length test
    A litmus paper helps in identifying acids and bases. In this context, litmus is derived from which of the following?
    • AIt is a synthetic compound created in the laboratory
    • BIt is a compound derived from animal fat
    • CIt is derived from a special type of seaweed
    • DIt is a natural dye extracted from lichens
    Answer: (D) It is a natural dye extracted from lichens
    Explanation

    Option d is the correct litmus is a natural dye extracted from lichens. It has (purple) colour in distilled water. When added acidic solution, it turns red and when added to a it turns blue. It is available in the form of a in the form of strips of paper, known as litmus it is available as red and blue litmus paper. Important Tips Other few important applications of lichens are: Lichens are highly sensitive to changes in air quality and can be used as indicators of pollution levels. Some lichens have been traditionally used as a source of natural dyes. Lichens have been used in traditional medicine by various cultures. Lichens are sometimes used as a source of aromatic compounds in the perfume industry. Lichens play a crucial role in soil formation and stabilization

38. #78Full-length test
    As per some recent reports there has been a decline in the nitrogen in natural ecosystems. In this context what will be its impact? 1. Shunted growth of trees 2. Increase in yield of agricultural crops 3. May reduce growth and reproduction in insects and birds in the long term. 4. Increase in the ability of plants to absorb carbon dioxide from the atmosphere.Select the correct answer using the codes given below
    • A1 and 2 only
    • B1 and 3 only
    • C2, 3 and 4 only
    • D1, 2 and 4 only
    Answer: (B) 1 and 3 only
    Explanation

    Option b is the correct makes up 79 percent of Earth's atmosphere and essential element for the growth of plants and availability can limit growth of primary most of the world's aquatic and terrestrial I is correct: Decline in the nitrogen in will lead to less availability of nitrogen to grassland. Plants that are deficient in nitrogen growth, depending on the severity of the growth is inhibited; younger leaves are inhibited Longitudinal shoot growth is inhibited, as is in 2 is In an ecosystem of little ciurnot thrive, and it will lead to low crop that do not have enough nitrogen become do not grow well and may have smaller flowers 3 is correct: When nitrogen is less available, thing holds on to the element for longer, slowing of nitrogen from one organism to another through interaction in the food chain. Reduced availability will make leaves of plants less nutritious to reducing growth

39. #79Full-length test
    Which among the following is the correct sequence of increasing order in terms of Global Warming Potential of the Greenhouse gases?
    • ASulfur hexafluoride Nitrous Oxide Methane Carbon dioxide
    • BSulfur hexafluoride Methane Nitrous Oxide Carbon dioxide
    • CCarbon dioxide Nitrous Oxide Methane Sulfur hexafluoride
    • DCarbon dioxide Methane Nitrous Oxide Sulfur hexafluoride
    Answer: (D) Carbon dioxide Methane Nitrous Oxide Sulfur hexafluoride
    Explanation

    Option d is the correct dis correct. The Global Warming Potential developed to allow comparisons of the global of different gases. Specifically, it is a measure of energy the emissions of 1 ton of a gas will absorb given period of time, relative to the emissions of 1 ton dioxide larger the GWP, the more that a given gas warms compared to CO2 over that time period. The usually used for GWPs is 100 years. GWPs common unit of measure, which allows analysts to emissions estimates of different gases (e.g., to national GHG inventory), and allows policymakers emissions reduction opportunities across dioxide Methane Nitrous Oxide is the correct sequence. GHG G WP for 100 years CO2 1 CH; 23 N20 296 HFC-23 1300 SF6 Source: IPCC Third Assessment Report (2001)

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