Chemistry GK Questions Quiz-5

Chemistry GK Questions Quiz-5

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

    81. PVC is obtained by the polymerisation of

    (1) Propane 
    (2) Vinyl chloride
    (3) Styrene 
    (4) Acetylene
    Answer:
    81. (2) Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride (VCM). Polyvinyl chloride, commonly abbreviated PVC, is the thirdmost widely produced plastic, after polyethylene and polypropylene. PVC is used in construction because it is cheaper and stronger than more traditional alternatives such as copper or ductile iron. It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is used in clothing and upholstery, electrical cable insulation, inflatable products and many applications in which it replaces rubber.



     82. Which amidst the following is nota gem stone ?

    (1) Cat’s-eye 
    (2) Topaz
    (3) Opal 
    (4) Pearl
    Answer:
    82. (1) A gemstone or gem (also called a precious or semiprecious stone, a fine gem, or jewel) is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments. However certain rocks (such as lapis lazuli) and organic materials (such as amber or jet) are not minerals, but are still used for jewelry, and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Topaz, Opal and Pearl are gemstones but Cat’s-eye is not a gem stone.


    83. Which of the following vegetable oils does not contain essential fatty acids ?

    (1) Sunflower oil 
    (2) Mustard oil
    (3) Coconut oil 
    (4)Groundnut oil
    Answer:
    83. (1) Fatty Acids are aliphatic carboxylic acid with varying hydrocarbon lengths at one end of the chain joined to terminal carboxyl (-COOH) group at the other end. The general formula is R-(CH2)n-COOH. Fatty acids are predominantly unbranched and those with even numbers of carbon atoms between 12 and 22 carbons long react with glycerol to form lipids (fat-soluble components of living cells) in plants, animals, and microorganisms. Sunflower oil is high in the essential vitamin E and has no essential saturated fat.


    84. The metallic constituents of hard water are :

    (1) Magnesium, calcium and tin
    (2) Iron, tin and calcium
    (3) Calcium, magnesium and iron
    (4) Magnesium, tin and iron
    Answer:
    84. (3) Hard water is water that has high mineral content. In domestic settings, hard water is often indicated by a lack of suds formation when soap is agitated in water. Wherever water hardness is a concern, water softening is commonly used to reduce hard water’s adverse effects. Water’s hardness is determined by the concentration of multivalent cations in the water. Multivalent cations are cations (positively charged metal complexes) with a charge greater than 1+. Usually, the cations have the charge of 2+. The metallic constituents of hard water are Calcium, magnesium and iron.


    85. The pH of human blood is between :

    (1) 6.5-7 
    (2) 7.5-8
    (3) 8-9 
    (4) 4.5-5
    Answer:
    85. (2) Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. Blood pH is regulated to stay within the narrow range of 7.5 to 8. Blood that has a pH below 7.5 is too acidic, whereas blood pH above 7.5 is too alkaline. Blood pH, partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and HCO3– are carefully regulated by a number of homeostatic mechanisms, which exert their influence principally through the respiratory system and the urinary system in order to control the acid-base balance and respiration.


    86. Which of the following imparts deep blue colour to glass ?

    (1) Cobalt oxide
    (2) Cupric oxide
    (3) Ferrous oxide
    (4) Nickel oxide
    Answer:
    86. (4) Glass colouring and colour marking may be obtained by addition of colouring ions, by precipitation of nanometer sized colloides (so-called striking glasses such as “ruby gold” or red “selenium ruby”), by coloured inclusions (as in milk glass and smoked glass), by light scattering (as in phase separated glass), by dichroic coatings , by coloured coatings. Nickel oxide produces deep blue glass.


    87. Which of the following fibres catches fire least ?

    (1) Nylon 
    (2) Cotton
    (3) Rayon 
    (4) Terricot
    Answer:
    87. (2) The fibre least prone to catch fire is cotton. Fabrics with more of the fiber surface area exposed to air have more oxygen available to support burning and therefore burn more easily. Thus, thin, gauzy fabrics, lace, or brushed fabrics can be very flammable. Fabrics with a napped or brushed surface of fine fibers can catch fire easily because of the greater amount of fiber surface exposed to oxygen in the air.


    88. Which of the following is used as filler in tyre of rubber ?

    (1) Carbon black 
    (2) Coal
    (3) Coke 
    4) Graphite
    Answer:
    88. (1) The most common use (70%) of carbon black is as a pigment and reinforcing phase in automobile tires. Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage and increasing tire life. Carbon black particles are also employed in some radar absorbent materials and in photocopier and laser printer toner. It is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil.


    89. Which of the following alloy is used in making magnet ?

    (1) Duralumin 
    (2) Stainless steel
    (3) Elniko 
    (4) Magnalium
    Answer:
    89. (3) A magnetic alloy is a combination of various metals from the periodic table that contains at least one of the three main magnetic elements: iron (Fe), nickel (Ni), and cobalt (Co). Such an alloy must contain but is not limited to one or more of these metals. Magnetic alloys have become common, especially in the form of steel (iron and carbon) alnico (iron, nickel, cobalt, and aluminum,) and permalloy (iron and nickel.) The strongest magnetic element is iron, which allows items made out of these alloys to attract to magnets.


    90. Milk tastes sour when it is left in open for some time. This happens due to the formation of

    (1) Lactic acid 
    (2) Citric acid
    (3) Acetic acid 
    (4) Carbonic acid
    Answer:
    90. (1) Milk contains a sugar called lactose, a disaccharide (compound sugar) made by the glycosidic bonding between glucose and glactose (monosaccharides). When milk is heated to a temperature of 30-40 degrees centigrade and a small amount of old curd added to it, the lactobacillus in that curd sample gets activated and multiplies. These convert the lactose into lactic acid, which imparts the sour taste to curd.



    91. The polymerisation of which of the following is used in manufacturing of polythene in industry ?

    (1) Methane 
    (2) Styrene
    (3) Acetylene 
    (4) Ethylene
    Answer:
    91. (4) Ethylene is a rather stable molecule that polymerizes only upon contact with catalysts. The
    conversion is highly exothermic, that is the process releases a lot of heat. Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. The most common catalysts consist of titanium (III) chloride, the so-called Ziegler-Natta catalysts. Another common catalyst is the Phillips catalyst, prepared by depositing chromium (VI) oxide on silica. Ethylene can be produced through radical polymerization, but this route is only limited utility and typically requires high pressure apparatus.


    92. Which of the following chemical materials is responsible for the depletion of ozone layer in the atmosphere ?

    (1) Nitrous oxide
    (2) Carbon dioxide
    (3) Chlorofluorocarbon
    (4) Sulphur dioxide
    Answer:
    92. (3) Chlorofluorocarbons (CFCs) and other halogenated ozone depleting substances (ODS) are mainly responsible for man-made chemical ozone depletion. CFCs were invented by Thomas Midgley, Jr. in the 1920s. They were used in air conditioning and cooling units, as aerosol spray propellants prior to the 1970s, and in the cleaning processes of delicate electronic equipment. They also occur as by-products of some chemical processes. No significant natural sources have ever been identified for these compounds their presence in the atmosphere is due almost entirely to human manufacture.


    93. Which of the following is the main nitrogenous waste in humans ?

    (1) Ammonia
    (2) Urea
    (3) Uric Acid
    (4) Ammonium Nitrate
    Answer:
    93. (3) The excretory system functions in ridding the body of nitrogenous (nitrogen-containing, discussed below) and other wastes. Nitrogenous wastes of animals are excreted in form of ammonia, urea, or uric acid. They are excreted in the urine. Because ammonia is so water-soluble, aquatic animals often can get rid of it just by diffusion into the surrounding water. That’s one reason why the water in your aquarium gets “bad” and needs to be changed, and why not changing the water could kill the fish. However, ammonia doesn’t readily go from body fluids into air, so terrestrial animals need other ways of getting rid of nitrogenous wastes.


    94. Aspirin is

    (1) Methoxy benzoic acid
    (2) Methyl Salicilate
    (3) Acetyl Salicilic acid
    (4) Phenyl Salicilate
    Answer:
    94. (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. Aspirin was first isolated by Felix Hoffmann, a chemist with the German company Bayer in 1897. 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.


    95. Cloud is a colloidal dispersion of

    (1) Air in a dispersion medium of water
    (2) Fog in a dispersion medium of water
    (3) Mist in a dispersion medium of air
    (4) Water drops in a dispersion medium of air
    Answer:
    95. (4) A colloid is a substance microscopically dispersed evenly throughout another substance. A colloidal system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium) in which the colloid is dispersed. A colloidal system may be solid, liquid, or gas. Cloud is a colloidal dispersion of Water drops in a dispersion medium of air.


    96. Which of the following is the petroleum wax ?

    (1) Bees wax
    (2) Carnauba wax
    (3) Paraffin wax
    (4) Jojoba wax
    Answer:
    96. (3) Waxes are a class of chemical compounds that are plastic (malleable) near ambient temperatures. Characteristically, they melt above 45 °C (113 °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. Although most natural waxes are esters, paraffin waxes are hydrocarbons, Paraffin waxes are mixtures of saturated and iso-alkanes, naphthenes, and alkyl- and naphthene-substituted aromatic compounds.


    97. Which variety of coal contains recognisable traces of the original plant material ?

    (1) Anthracite 
    (2) Lignite
    (3) Peat 
    (4) Bitumen
    Answer:
    97. (3) Peat contains recognizable traces of the original plant material. Initially the peat is converted into lignite or ‘brown coal’ - these are coal-types with low organic maturity. In comparison to other coals, lignite is quite soft and its colour can range from dark black to various shades of brown.


    98. Which is the purest form of iron ?

    (1) Steel 
    (2) Cast iron
    (3) Pig iron 
    (4) Wrought iron
    Answer:
    98. (4) Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element (by mass) forming the planet Earth as a whole, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Wrought iron is the purest form of iron. It contains less than 0.25% carbon .


    99. Which of the following metals form an amalgam with other metals ?

    (1) Lead 
    (2) Tin
    (3) Zinc 
    (4) Mercury
    Answer:
    99. (4) An amalgam is a substance formed by the reaction of mercury with another metal. Almost all metals can form amalgams with mercury, notable exception being iron. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc. Amalgam is an “excellent and versatile restorative material” and is used in dentistry for a number of reasons.


    100. Detergents used for cleaning clothes and utensils contain

    (1) nitrates
    (2) bicarbonates
    (3) sulphonates
    (4) bismuthates
    Answer:
    100. (3) Sulphonate is a detergent used for cleaning clothes and utensils. It is a salt or ester of any sulphonic acid containing the ion RSO2– or the group RSO2–, R being an organic group. , it is used as comonomers in LLDPE and HDPE (C4–C8, in manufacture of lubricants (C^-C^). and industrial chemicals and plasticisers.


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