Chemistry GK Questions Quiz-11

Chemistry GK Questions Quiz-11

Chemistry Multiple Choice Questions (MCQs) Quiz for State and UPSC Civil Services Examinations. Objective Questions on Chemistry for competitive examinations.

    201. Candle is a mixture of

    (1) Paraffin was and stearic acid
    (2) Bees wax and stearic acid
    (3) Higher fatty acids and stearic acid
    (4) Bees wax and paraffin wax
    Answer:
    201. (1) The candle can be made of paraffin (a byproduct of petroleum refining), microcrystalline wax, stearin (now produced almost exclusively from palm waxes though initially manufactured from animal fats), beeswax (a byproduct of honey collection), gel (a mixture of polymer and mineral oil), some plant waxes (generally palm, carnauba, bayberry, or soybean wax), tallow (rarely used since the introduction of affordable and cheap wax alternatives) or spermaceti (extracted from the head of a Sperm Whale). The size of the flame and corresponding rate of burning is controlled largely by the candle wick. The most basic production method of candles generally entails melting the solid fuel by the controlled application of heat. The liquid is then poured into a mould or a wick is repeatedly immersed in the liquid to create a dipped tapered candle. Often fragrance oils, essential oils or anilinebased dye is added.

    202. Ethanol containing 5% water is known as

    (1) rectified spirit
    (2) denatured spirit
    (3) methylated alcohol
    (4) power alcohol
    Answer:
    202. (1) A rectified spirit, rectified alcohol, or neutral spirit is highly concentrated ethanol which has been purified by means of repeated distillation, a process that is called rectification. It typically contains 95% alcohol by volume (ABV). Rectified spirits are used in mixed drinks, in the production of liqueurs, for medicinal purposes, and as a household solvent. The purity of rectified spirit has a practical limit of 95.6% ABV (191.2 US proof) when produced using conventional distillation processes, because a mixture of ethanol and water becomes an azeotrope at this concentration. Neutral grain spirits are rectified spirits made from grain. However, rectified spirits are also made from other kinds of plant material, such as sugar beets, potatoes, and sugar cane.

    203. The important ore of aluminium is

    (1) bauxite 
    (2) cryolite
    (3) fluorspar 
    (4) haematite
    Answer:
    203. (1) Bauxite is an aluminium ore and is the main source of aluminium. This form of rock consists mostly of the minerals gibbsite, boehmite and diaspore , in a mixture with the two iron oxides goethite and hematite, the clay mineral kaolinite, and small amounts of anatase TiO 2. Bauxite was named after the village Les Baux in southern France, where it was first recognised as containing aluminium and named by the French geologist Pierre Berthier in 1821. The lateritic bauxites are found mostly in the countries of the tropics. They were formed by lateritization of various silicate rocks such as granite, gneiss, basalt, syenite, and shale. In comparison with the iron-rich laterites, the formation of bauxites demands even more on intense weathering conditions in a location with very good drainage. This enables the dissolution of the kaolinite and the precipitation of the gibbsite. Zones with highest aluminium content are frequently located below a ferruginous surface layer.

    204. Aqua regia is a 1 : 3 mixture, by volume, of

    (1) conc. nitric acid and conc. hydrochloric acid
    (2) conc. hydrochloric acid and conc. nitric acid
    (3) conc. nitric acid and conc. sulphuric acid
    (4) conc. sulphuric acid and conc. nitric acid
    Answer:
    204. (1) Aqua regia or nitro-hydrochloric acid is a highly corrosive mixture of acids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or noble metals, gold and platinum. However, titanium, iridium, ruthenium, tantalum, osmium, rhodium and a few other metals are capable of withstanding its corrosive properties. Aqua regia is also used in etching and in specific analytic procedures. It is also used in some laboratories to clean glassware of organic compounds and metal particles. This method is preferred over the “traditional” chromic acid bath for cleaning NMR tubes, because no traces of paramagnetic chromium can remain to later spoil acquired spectra.

    205. What is the maximum Water Vapour content in the atmosphere?

    (1) 2 to 3 per cent
    (2) 3 to 4 per cent
    (3) 4 to 5 per cent
    (4) 5 to 6 per cent
    Answer:
    205. (2) The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth’s gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around 1% and maximum upto 4%. While air content and atmospheric pressure vary at different layers, air suitable for the survival of terrestrial plants and terrestrial animals is currently only known to be found in Earth’s troposphere and artificial atmospheres.

    206. The amount of chlorine available in water after disinfection is called as

    (1) free chlorine
    (2) residual chlorine
    (3) free available chlorine
    (4) combined available chlorine
    Answer:
    206. (2) The word “residual” means “remainder” or “that which is left”, and as the name suggests the chlorine residual is measure of the amount of chlorine remaining in the water after disinfection. The chlorine residual is usually tested in finished water which is ready to be released into the distribution system, although operators must also ensure that there is adequate residual at the extreme ends of the
    distribution system. Tests for chlorine residual are probably the most frequently performed tests at water treatment plants. There are three types of chlorine residual which must be considered in water treatment. Free chlorine residual - residual consisting of dissolved chlorine gas, Hypochlorous acid, and hypochlorite ions, Combined chlorine residual - residual consisting of other forms of chlorine such as chloramines which are capable of killing bacteria and oxidizing organic matter, Total chlorine residual - the sum of the free chlorine residual and the combined chlorine residual.

    207. What are the major pollutants of cigarette smoke?

    (1) Carbon monoxide and dioxin
    (2) Carbon monoxide and nicotine
    (3) Carbon monoxide and benzene
    (4) Dioxin and benzene
    Answer:
    207. (2) Particulate matter consists of millions of tiny particles of diverse chemical composition. Particulate matter from tobacco smoke includes many particles in the size range that reflects light, which explains why tobacco smoke is easily seen by the eye. In contrast to smoke particles, gases emitted by the cigarette such as benzene and carbon monoxide (CO) are invisible to the eye. Particles smaller than 2.5 micrometers (PM2.5) are major components of cigarette smoke and can enter deep into the lung where they can cause serious health problems. The pollutants generated by the cigarette arise from the chemical process of burning organic matter, or combustion of tobacco and paper. Combustion processes, such as wood burning or waste incineration, emit thousands of pollutants, some of which are in the gas phase and some of which are in the form of small particles called particulate matter.

    208. Nuclear energy is a mineral based energy source. It is derived from

    (1) uranium 
    (2) thorium
    (3) plutonium 
    (4) All of the above
    Answer:
    208. (1) The sun and stars are seemingly inexhaustible sources of energy. That energy is the result of nuclear reactions, in which matter is converted to energy. We have been able to harness that mechanism and regularly use it to generate power. Presently, nuclear energy provides for approximately 16% of the world’s electricity. Unlike the stars, the nuclear reactors that we have today work on the principle of nuclear fission. Scientists are working like madmen to make fusion reactors which have the potential of providing more energy with fewer disadvantages than fission reactors. Nuclear Fission: In nuclear fission, the nuclei of atoms are split, causing energy to be released. The atomic bomb and nuclear reactors work by fission. The element uranium is the main fuel used to undergo nuclear fission to produce energy since it has many favorable properties. Uranium nuclei can be easily split by shooting neutrons at them. Also, once a uranium nucleus is split, multiple neutrons are released which are used to split other uranium nuclei. This phenomenon is known as a chain reaction.

    209. Zinc sulphide is commonly used as

    (1) fungicide 
    (2) herbicide
    (3) rodenticide
    (4) deodorant
    Answer:
    209. (3) Rodenticides are a category of pest control chemicals intended to kill rodents. Metal phosphides have been used as a means of killing rodents and are considered single-dose fast acting rodenticides (death occurs commonly within 1-3 days after single bait ingestion). A bait consisting of food and a phosphide (usually zinc phosphide) is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. This method of vermin control has possible use in places where rodents are resistant to some of the anticoagulants, particularly for control of house and field mice; zinc phosphide baits are also cheaper than most second-generation anticoagulants, so that sometimes, in the case of large infestation by
    rodents, their population is initially reduced by copious amounts of zinc phosphide bait applied, and the rest of population that survived the initial fast-acting poison is then eradicated by prolonged feeding on
    anticoagulant bait.

    210. The purest form of water is

    (1) tap water
    (2) rain water
    (3) ground water
    (4) distilled water
    Answer:
    210. (2) Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystem, as well as water for hydroelectric power plants and crop irrigation. The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as
    cumulonimbus (thunder clouds) which can organize into narrow rain bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at
    elevation which forces moist air to condense and fall out as rainfall along the sides of mountains.

    211. The main constituent of biogas is

    (1) oxygen 
    (2) methane
    (3) acetic acid 
    (4) methyl alcohol
    Answer:
    211. (2) Biogas typically refers to a gas produced by breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal feces, and kitchen waste can be converted into a gaseous fuel called biogas. Biogas originates from biogenic material and is a type of bio fuel. Biogas is produced by the anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material, and crops. Biogas comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel. Biogas can be used as a fuel in any country for any heating purpose, such as cooking.

    212. Aspirin is chemically known as

    (1) methyl salicylate
    (2) hydroxysalicylate
    (3) acetylsalicylic acid
    (4) alkylsalicylic acid
    Answer:
    212. (3) Aspirin (USAN), also known as acetylsalicylic acid, is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. Salicylic acid, the main metabolite of aspirin, is an integral part of human and animal metabolism. While in humans much of it is attributable to diet, a substantial part is synthesized endogenously. Aspirin also has an anti-platelet effect by inhibiting the production of thromboxane, which under normal circumstances binds platelet molecules together to create a patch over damaged walls of blood vessels. Because the platelet patch can become too large and also block blood flow, locally and downstream, aspirin is also used long-term, at low doses, to help prevent heart attacks, strokes, and blood clot formation in people at high risk of developing blood clots.

    213. The most abundant element in the human body is

    (1) carbon 
    (2) iron
    (3) nitrogen 
    (4) oxygen
    Answer:
    213. (4) The composition of the human body can be looked at from the point of view of either mass composition, or atomic composition. To illustrate both views, the human body is 70% water, and water is 11% hydrogen by mass but 67% hydrogen by atomic percent. Thus, most of the mass of the human body is oxygen, but most of the atoms in the human body are hydrogen atoms. Almost 99% of the mass of the human body is made up of the six elements oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All are necessary to life. The remaining elements are trace elements, of which more than a dozen are thought to be necessary for life, or play an active role in health (e.g., fluorine, which hardens dental enamel but seems to have no other function).

    214. Which of the following is not a greenhouse gas ?

    (1) Hydrogen
    (2) Carbon dioxide
    (3) Nitric oxide
    (4) Chlorofluorocarbon
    Answer:
    214. (1) A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth’s atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. In the Solar System, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth’s surface would average about 33 degree C (91 degree F) colder than the present average of 14 degree C (57 degree F). However, since the beginning of the Industrial Revolution, the burning of fossil fuels has contributed to the increase in carbon dioxide in the atmosphere from 280 ppm to 397 ppm. 

    215. Wax used for making candle is chemically a mixture of

    (1) aliphatic hydrocarbons
    (2) aromatic hydrocarbons
    (3) cyclic hydrocarbons
    (4) aliphatic and aromatic hydrocarbons
    Answer:
    215. (1) An aliphatic compound is a hydrocarbon compound containing carbon and hydrogen joined together in straight chains, branched trains or non-aromatic rings. Waxes are a class of chemical compounds that are plastic (malleable) near ambient temperatures. Characteristically, they melt above 45 degree C (113 degree F) to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, non-polar solvents. All waxes are organic compounds, both synthetic and naturally occurring. Waxes are organic compounds that characteristically consist of long alkyl chains. Natural waxes are typically esters of fatty acids and long chain alcohols. Synthetic waxes are longchain hydrocarbons lacking functional groups. Waxes are biosynthesized by many plants and animals. They typically consist of several components, including wax esters, wax acids, wax alcohols, and hydrocarbons. Wax esters are typically derived from a variety of carboxylic acids and a variety of fatty alcohols.

    216. Litmus is obtained from

    (1) a bacterium 
    (2) a fungus
    (3) an alga 
    (4) lichen
    Answer:
    216. (4) Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccellatinctoria. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic (i.e. alkaline) conditions, with the colour change occurring over the pH range 4.5-8.3 at 25 degree C. Neutral litmus paper is purple. Litmus can also be prepared as an aqueous solution that functions similarly. Under acidic conditions the solution is red, and under basic conditions the solution is blue. The main use of litmus is to test whether a solution is acidic or basic. Wet litmus paper can also be used to test water-soluble gases; the gas dissolves in the water and the resulting solution colours the litmus paper. For instance, ammonia gas, which is alkaline, colours the red litmus paper blue.

    217. Vinegar made by fermentation from cane sugar contains

    (1) palmitic acid 
    (2) lactic acid
    (3) citric acid 
    (4) acetic acid
    Answer:
    217. (4) Vinegar is a liquid substance consisting mainly of acetic acid (CH3CO2H) and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. It is today mainly used in the kitchen as a general cooking ingredient, but historically, as the most easily available mild acid, it had a great variety of industrial, medical, and domestic uses, some of which (such as a general household cleanser) are still promoted today. Commercial vinegar is produced either by fast or slow fermentation processes. In general, slow methods are used with traditional vinegars, and fermentation proceeds slowly over the course of weeks or months. The longer fermentation period allows for the accumulation of a nontoxic slime composed of acetic acid bacteria. Fast methods add mother of vinegar (i.e., bacterial culture) to the source liquid before adding air using a venturi pump system or a turbine to promote oxygenation to obtain the fastest fermentation.

    218. Photooxidation process is initiated by

    (1) light 
    (2) heat
    (3) oxygen 
    (4) catalyst
    Answer:
    218. (1) Oxidation is a process in which something (an atom or molecule or substance) loses an electron to something else. Photo-oxidation is therefore the process of oxidation which is caused by shining light on it. Often, light can be used to cause reactions to happen, such as oxidation. The term “photo” comes from “photon” which is light. The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of polymers. Photo-oxidation is a chemical change that reduces the polymer’s molecular weight. As a consequence of this change the material becomes more brittle, with a reduction in its tensile, impact and elongation strength. Discolouration and loss of surface smoothness accompany photo-oxidation. High temperature and localized stress concentrations are factors that significantly increase the effect of photo-oxidation.

    219. Ultraviolet radiation striking the earth is due to the depletion of

    (1) carbon monoxide
    (2) carbon dioxide
    (3) ozone
    (4) oxygen
    Answer:
    219. (3) Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidizing potential, however, causes ozone to damage mucus and respiratory tissues in animals, and also tissues in plants, above concentrations of about 100 parts per billion. This makes ozone a potent respiratory hazard and pollutant near ground level. However, the so-called ozone layer (a portion of the stratosphere with a higher concentration of ozone, from two to eight ppm) is beneficial, preventing damaging ultraviolet light from reaching the Earth’s surface, to the benefit of both plants and animals. Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth’s atmosphere. In total, ozone makes up only 0.6 parts per million of the atmosphere.

    220. Major gaseous pollutant of the thermal power station is

    (1) H2S 
    (2) NH3
    (3) NO2 
    (4) SO2
    Answer:
    220. (4) A flue-gas stack is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas, wood or any other fuel is combusted in an industrial furnace, a power plant’s steam-generating boiler, or other large combustion device. Flue gas is usually composed of carbon dioxide (CO2) and water vapor as well as nitrogen and excess oxygen remaining from the intake combustion air. It also contains a small percentage of pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulfur oxides. The flue gas stacks are often quite tall, up to 400 metres (1300 feet) or more, so as to disperse the exhaust pollutants over a greater area and thereby reduce the concentration of the pollutants to the levels required by governmental environmental policy and environmental regulation.


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