HCS Exam: MCQ Series Chemistry Part-IV
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Chemistry Multiple Choice Questions For HCS Exam
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Important 20000 MCQ Series For HCS Exam: CHEMISTRY PART-IV
Q1.Which of the following alkali metals has highest specific heat?
Explanation: Lithium has the highest specific heat capacity of any solid element. Because of its specific heat capacity, the highest of all solids, lithium metal is often used in coolants for heat transfer applications. It belongs to the alkali metal group of chemical elements. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable. For this reason, it is typically stored in mineral oil.
Q2.In which of the following substances all carbon atoms are quaternary in nature?
Explanation: carbon atoms in diamond are quaternary in nature. The crystal structure of a diamond is a face-centered cubic or FCC lattice. Each carbon atom joins four other carbon atoms in regular tetrahedrons (triangular prisms). Based on the cubic form and its highly symmetrical arrangement of atoms, diamond crystals can develop into several different shapes, known as ‘crystal habits’.
Q3.Which of the following is' a natural dye?
(a) Crystal violet
(b) Aniline blue
Explanation: Alizarin or 1,2-dihydroxyanthraquinone (also known as Mordant Red 11 and Turkey Red is an organic compound with formula C14 H8 O4 that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus. In 1869, it became the first natural pigment to be duplicated synthetically.Alizarin is the main ingredient for the manufacture of the madder lake pigments known to painters as Rose madder and Alizarin crimson. Alizarin in the most common usage of the term has a deep red colour, but the term is also part of the name for several related non-red dyes, such as Alizarine Cyanine Green and Alizarine Brilliant Blue.
Q4. The ratio of pure gold in 18 carat gold is:
Explanation: The gold content of alloys is measured in carats (k). Pure gold is designated as 24k where the ratio of pure gold is supposed to be 100 per cent. So 18 k gold will have pure gold ratio of 75 per cent.
Q5. Diamond is harder than graphite because of:
(a) difference in layers of atoms
(b) tetrahedral structure of diamond
(c) difference of crystalline structures
(d) None of these
Explanation: Diamond is harder than graphite because diamond has a more complex structure. Diamond’s structure is like many pentagons connected together, each pentagon sharing a side with another pentagon or each pentagon sharing a point with another pentagon. All the points are linked together in some way. Graphite’s structure is very loose, with its bonds forming layers. There will be one sheet of elements bonded together, but then another sheet of bonds of elements will lay on top of that, and there will be very weak bonds holding those sheets together.
Q6. What is the element required for solar energy conversion?
(d) Ultra pure carbon
Explanation: The most prevalent bulk material for solar cells is crystalline silicon (abbreviated as a group as c-Si), also known as “solar grade silicon”. Bulk silicon is separated into multiple categories according to crystallinity and crystal size in the resulting ingot, ribbon, or wafer.
Q7. Which of the following type of coal has the lowest proportion of volatile matter?
Explanation: Anthracite has the lowest proportion of volatile matter. Volatile matter in coal refers to the components of coal, except for moisture, which are liberated at high temperature in the absence of air. This is usually a mixture of short and long chain hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter of coal is determined under rigidly controlled standards.
Q8. Saccharin is made up of
Explanation: Saccharin can be produced in various ways. The original route by Remsen &Fahlberg starts with toluene. Saccharin is an artificial sweetener. The basic substance, benzoic sulfilimine, has effectively no food energy and is much sweeter than sucrose, but has a bitter or metallic aftertaste, especially at high concentrations. It is used to sweeten products such as drinks, candies, cookies, medicines, and toothpaste.
Q9.PVC is obtained by the polymerisation of
(b) Vinyl chloride
Explanation: 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.
Q10.L.P.G. is a hydrocarbon consisting of a mixture of:
(a) Methane and Butane
(b) Propane and Butane
(c) Ethane and Propane
(d) Ethane and Butane
Explanation: LPG is a mixture of C4H10 (Butane), C3H8 (propane) and C2H6 (ethane). Main constituent is butane (C4H10).
Q11.Which of the following vegetable oils does not contain essential fatty acids?
(a) Sunflower oil
(b) Mustard oil
(c) Coconut oil
(d) Groundnut oil
Explanation: 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.
Q12.The metallic constituents of hard water are:
(a) Magnesium, calcium and tin
(b) Iron, tin and calcium
(c) Calcium, magnesium and iron
(d) Magnesium, tin and iron
Explanation: 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.
Q13.The pH of human blood is between:
Explanation: Different fluids in the human body generally have a delicate range of acid-alkaline balance they maintain for optimal functioning. Human blood has a normal pH of about 7.41. The pH of urine has a wider range. Normal ranges for urine pH are from 4.5 to 8. When the pH levels of blood or other key bodily fluids fall out of optimal pH range due to adverse metabolic or respiratory conditions, the human body goes through a variety of adjustments to try to correct the acid or alkaline imbalance. If the body is too alkaline, a condition called alkalosis results. Conversely, an overly acid condition results in acidosis.
Q14.Which of the following imparts deep blue colour to glass?
(a) Cobalt oxide
(b) Cupric oxide
(c) Ferrous oxide
(d) Nickel oxide
Explanation: The addition of oxides, sulfides, salts, and other compounds of different metals to molten glass at the time of manufacture adds colour to glass. The introduction of electrically charged ions which are evenly distributed in the glass during manufacture also gives glass a characteristic colour. Cobalt oxide: deep blue colour; copper oxide: turquoise; chromium: dark green to black; cadmium sulfide: deep yellow, etc.
Q15.Which of the following fibres catches fire least?
Explanation: 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.
Q16.Which of the following is used as filler in tyre of rubber?
(a) Carbon black
Explanation: 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.
Q17.Which of the following alloy is used in making magnet ?
(b) Stainless steel
Explanation: 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.
Q18.Milk tastes sour when it is left in open for some time. This happens due to the formation of
(a) Lactic acid
(b) Citric acid
(c) Acetic acid
(d) Carbonic acid
Explanation: 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.
Q19.The polymerisation of which of the following is used in manufacturing of polythene in industry?
Explanation: 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.
Q20. Which of the following chemical materials is responsible for the depletion of ozone layer in the atmosphere?
(a) Nitrous oxide
(b) Carbon dioxide
(d) Sulphur dioxide
Explanation: Chlorofluorocarbons (CFCs) and other halogenated ozone-depleting substances (ODS) are mainly responsible for man-made chemical ozone depletion.
Q21.Which of the following is the main nitrogenous waste in humans?
(c) Uric Acid
(d) Ammonium Nitrate
Explanation: 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.
Q22.Cloud is a colloidal dispersion of
(a) Air in a dispersion medium of water
(b) Fog in a dispersion medium of water
(c) Mist in a dispersion medium of air
(d) Water drops in a dispersion medium of air
Explanation: 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.
Q23.Which of the following is the petroleum wax?
(b) Camauba Wax
(c) Paraffin wax
(d) Jojoba wax
Explanation: 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.
Q24.Which variety of coal contains recognizable traces of the original plant material?
Explanation: 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.
Q25.Which is the purest form of iron?
(b) Cast iron
(c) Pig iron
(d) Wrought iron
Explanation: Wrought iron or malleable iron is the purest form of commercial iron as it contains the lowest percentage of carbon (0.12-0.25%) and impurities of S, P, Mn and Si in minute amount (about 0.3%). It is made by melting cast iron with scrap iron in a reverberatory furnace lined with Fe2O3 which oxidizes C, Si, P, etc, most of which are then removed by rolling.
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