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Part 068 – Chemistry Previous Year Questions

Q1. Which of the following is used to make light weight, but strong plastic ?
(a) Nylon
(b) Polythene
(c) Polyvinyl Chloride
(d) Methyl Methacrylate
Ans: (c) Polyvinyl chloride (PVC) is a common, strong but lightweight plastic that is used in making tough plastic. It is used for flexible applications such as insulating cables. It is the third-most widely produced synthetic plastic polymer, after polyethylene and polyprop-ylene.

Q2. Which of the following is the correct sequence of countries in terms of maximum carbon dioxide emission?

(a) China, USA, European Union, India
(b) USA, India, China, European Union
(c) China, India, European Union, USA
(d) European Union, China, USA, India
Ans: (a) According to the EDGAR database released by European Commission and Netherlands Environmental Assessment Agency in 2014, China, USA, European Union, India and Russia are the largest emitters of carbon emission (annual CO2 emissions estimates in thousands of CO2 tonnes) across the globe. Country O2 emissions (kt) in 2014 World 35,669,000 China 10,540,000 United States 5,334,000 European Union 3,415,000 India 2,341,000 Russia 1,766,000 Japan 1,278,000 Germany 767,000

Q3. Which of the following substance’s smell is similar to Ethanoic acid?

(a) Tomato juice (b) Kerosene
(c) Vinegar (d) Lemon
Ans: (c) Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell.Vinegar is roughly 3–9% acetic acid by volume, making acetic acid the main component of vinegar apart from water.

Q4. Which of the following acids serves as an electrolyte in a lead storage battery?

(a) Sulphuric acid
(b) Lactic acid
(c) Hydrochloric acid
(d) Nitric acid
Ans: (a) Dilute sulfuric acid (H2SO4) serves as the electrolyte in a lead-acid battery. Dilute sulfuric acid used for lead acid battery has ratio (to water) of 3:1 other components of the battery include: Lead peroxide (PbO2) and Sponge lead (Pb).

Q5. Which of the following is not a natural source of hydrocarbon?

(a) Natural Gas (b) Coal
(c) Petroleum (d) Mica
Ans: (d) There are three main natural sources of hydrocarbons: natural gas, petroleum and coal.Mica is a natural occurring mineral that is based on a collection of silicate minerals and composed of varying amounts of potassium, iron, aluminum, magnesium and water. It is widely used in the electrical industry.

Q6. Helium is added to the oxygen supply of deep sea divers because it is

(a) less poisonous than nitrogen
(b) Lighter than nitrogen
(c) Readily miscible with oxygen
(d) less soluble in blood than nitrogen at high pressure
Ans: (d) Deep-sea divers have their oxygen supply mixed with helium in order to avoid the toxic nature of oxygen under extreme pressures. The Helium atom is much smaller than the Nitrogen molecule, has a smaller electron cloud and is less polarizable. It, therefore, is less soluble in blood than nitrogen and prevents the formation of nitrogen bubbles in blood which blocks blood flow as the diver comes to the surface of the sea from underwater.

Q7. Terylene is a condensation polymer of ethylene glycol and which acid?

(a) Benzoic Acid
(b) Salicylic acid
(c) Phthalic acid
(d) Terephthalic acid
Ans: (d) Terylene is a co-polymer of ethylene glycol and Terephthalic acid. Also known as Dacron, it is prepared by the condensation polymerization of ethylene glycerol and Terephthalic acid with elimination of water. The reaction is carried out at about 420-460 K in the presence of a catalyst consisting of a mixture of zinc acetate and antimony trioxide.

Q8. What are the components responsible for acid rain?

(a) Nitrogen monoxide (NO) and Carbon monoxide (CO)
(b) Sulphur dioxide (SO2) and Nitrogen oxides (NOx)
(c) Carbon dioxide (CO2) and Carbon monoxide (CO)
(d) Oxides of carbon (COx) and Oxides of nitrogen (NOx)
Ans: (b) Acid rain is caused by emissions of sulfur dioxide (SO2) and nitrogen oxide (NOx), which react with the water molecules in the atmosphere to produce acids.The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids.The chemicals in acid rain can cause paint to peel, corrosion of steel structures and weathering of stone buildings.

Q9. What is Zeolite?

(a) Hydrated Aluminosilicate
(b) Hydrated Calcium Sulphate
(c) Dehydrated Aluminosilicate
(d) Dehydrated Calcium Sulphate
Ans: (a) Zeolites are hydrated aluminosilicate minerals made from interlinked tetrahedra of alumina (AlO4) and silica (SiO4). In simpler words, they’re solids with a relatively open, three-dimensional crystal structure built from the elements aluminium, oxygen, and silicon, with alkali or alkaline-Earth metals (such as sodium, potassium, and magnesium) plus water molecules trapped in the gaps between them.

Q10. L.P.G. is mostly liquefied

(a) hydrogen (b) oxygen
(c) butane (d) methane
Ans: (c) Liquefied petroleum gas or liquid petroleum gas (LPG) is mostly propane (C3H8), or butane (C4H10). They are most commonly mixtures of these two hydrocarbon gases that are used as fuel in heating appliances, cooking equipment, and vehicles.In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane.

Q11. What is used in storage batteries?

(a) Copper (b) Tin
(c) Lead (d) Zinc
Ans: (c) The electrodes of the cells in a storage battery consist of lead grids. The openings of the anodic grid is filled with spongy (porous) lead. The openings of the cathodic grid is filled with lead dioxide (PbO2). Dilute sulfuric acid (H2SO4) serves as the electrolyte.Leadacid batteries, also known as lead storage batteries, can store a lot of charge and provide high current for short periods of time.

Q12. The biogas used for cooking is a mixture of which of the following ?

(a) Carbon dioxide and oxygen
(b) Isobutane and propane
(c) Methane and carbon monoxide
(d) Methane and carbon dioxide
Ans: (d) Biogas is essentially a mixture of Methane (CH4, around 55-75%) but also contains Carbon Dioxide (CO2), around 25-30%), varying quantities of Water (H2O) and Hydrogen Sulphide (H2S). Other compounds can also be found, especially in waste dump biogas: Ammonia (NH3), Hydrogen (H2), Nitrogen (N2) and Carbon Monoxide (CO). Methane is the valuable component under the aspect of using biogas fuel.

Q13. _____ gives hardness to stainless steel.

(a) Zinc (b) Lead
(c) Carbon (d) Tin
Ans: (c) Iron is alloyed with carbon lo make steel and has the effect of increasing the hardness and strength of iron. Pure iron cannot be hardened or strengthened by heat treatment but the addition of carbon enables a wide range of hardness and strength. High-carbon stainless steel contains a minimum of 0.3% carbon. The higher the carbon content, the less formable and the tougher the steel becomes.

Q14. Which of the following is not soluble in water ?

(a) Lead Sulphate
(b) Zinc sulphate
(c) Potassium sulphate
(d) Sodium sulphate
Ans: (b) Lead sulfate (PbSO4) is a white crystalline solid. It is insoluble in water and sinks in it. It is often seen in the plates/electrodes of car batteries, as it is formed when the battery is discharged. It is also known as fast white, milk white, sulfuric acid lead salt or anglesite.

Q15. Activated Charcoal is used to remove colouring matter from pure substances by

(a) Bleaching (b) Oxidation
(c) Adsorption (d) Reduction
Ans: (c) Heating wood to a very high temperature in the absence of air makes charcoal. When it is heated to an even higher temperature, about 930°C, impurities are driven from its surface and it becomes activated charcoal, sometimes called decolorizing charcoal. This activated charcoal can remove impurities in either the gaseous or liquid state from many solutions. It does so by the process of adsorption, or by attracting these molecules to the surface.

Q16. Chernobyl disaster is the result of pollution by

(a) Oil spill
(b) Acid rain
(c) Carbon dioxide
(d) Radioactive waste
Ans: (d) The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the city of Pripyat, then located in the Ukrainian USSR. An explosion and fire released large quantities of radioactive particles into the atmosphere, which spread over much of the western USSR and Europe.

Q17. Which of the following caused radioactive pollution along the coast of Kerala ?

(a) Plutonium (b) Zinc
(c) Thorium (d) Radium
Ans: (c) Thorium-rich monazite sand deposits on the Kerala coast has been responsible for natural radioactive contamination. It has been pronounced on the southwest coastal line of the state. The region has been found to have elevated levels of background radioactivity due to high abundance of thorium.

Q18. For extinguishing fire, we use

(a) Hydrogen
(b) Carbon Monoxide
(c) Carbon Dioxide
(d) Marsh gas
Ans: (c) Fire extinguishers use carbon dioxide to displace the oxygen necessary for a fire to burn, extinguishing the blaze. Fires need oxygen, fuel, and heat to ignite, and removing any one of those three components can put out a fire. It is useful for electrical fires and some flammable liquid fires, but may make some gasoline or paper fires worse by dispersing burning material.

Q19. The chemical name of quartz is

(a) Calcium oxide
(b) Calcium phosphate
(c) Sodium phosphate
(d) Sodium silicate
Ans: (d) Quartz is a compound of one part silicon and two parts of oxygen, silicon dioxide, SiO2. Quartz is the most abundant silica mineral. It is used in a number of industries, the important being glass, foundry, sodium silicate, silicon alloys, etc. The various grades of sodium silicate are characterized by their SiO2:Na2O weight ratio.

Q20. The depletion in Ozone layer is caused by ___________ .

(a) Nitrous oxide
(b) Carbon dioxide
(c) Chlorofluorocarbons
(d) Methane
Ans: (c) Chlorofluorocarbons (CFCs), also known as Freon, cause the breakdown of the ozone layer that protects the earth from the sun’s ultraviolet (UV) radiation.In the upper atmosphere, the UV-induced breakdown of CFCs releases free, highly reactive chlorine and bromine atoms that lead to the breakdown of the stratospheric ozone layer. Owing to ozone depletion in the upper atmosphere, CFCs have been phased out under the Montreal Protocol of 1987.

Q21. Phosphorus is kept in water because

(a) its ignition temperature is very high
(b) its ignition temperature is very low
(c) its critical temperature is high
(d) its critical temperature is low
Ans: (b) The allotropic form of Phosphorus (white phosphorus) is less stable and therefore highly reactive because of angular strain in P4 molecule where the angles are only 60o. Having very low ignition temperature, it readily catches fire in air to give dense white fumes of P4O10. So it is kept in water to avoid oxidation by the oxygen present in air.

Q22. Sea water is saltier than rain water because

(a) Sea animals are salt producing
(b) The air around the sea is saltish
(c) Rivers wash away salts from earth and pour them into the sea
(d) Sea beds have salt producing mines
Ans: (c) Seawater is salty because rainwater dissolves the salt minerals found in soil and rocks as it travels through rivers and streams en route to the sea The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid. The rain physically erodes the rock and the acids chemically break down the rocks and carries salts and minerals along in a dissolved state as ions. The ions in the runoff are carried to the streams and rivers and then to the ocean which makes them salty.

Q23. Even after sunset, the air near the Earth’s surface continue to receive heat due to

(a) Insolation
(b) Terrestrial Radiation
(c) Conduction
(d) Convection
Ans: (b) Even after the sunset when the sun goes down, the incoming radiation from the sun stops, but there is still a lot of radiation that has been absorbed by the earth, which is re-radiated in form of terrestrial radiation.Energy leaving the earth’s surface i.e. terrestrial radiation heats up the atmosphere more than the incoming solar radiation i.e. insolation

Q24. Trinitrotoluene is

(a) used to melt metals
(b) used to fuse two metals
(c) used as an abrasive
(d) used as an explosive
Ans: (d) Trinitrotoluene (C6H2(NO2)3CH3), abbreviated as TNT, is sometimes used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard measure of bombs and other explosives.

Q25. Nitrification is the biological process of converting

(a) N2 into nitrate
(b) N2 into nitrite
(c) Ammonia into nitrite
(d) Ammonia into N2
Ans: (c) Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification.Nitrification is an important step in the nitrogen cycle in soil.

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