Chemistry GK Questions Quiz-8

Chemistry GK Questions Quiz-8

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

    141. The gas used for filling weather balloons is

    (1) helium 
    (2) hydrogen
    (3) air 
    (4) nitrogen
    Answer:
    141. (1) A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig bladder. Some balloons are used for decorative purposes, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation. A balloon’s properties, including its low density and low cost, have led to a wide range of applications. Because of the non combustible property of the helium gas it is widely used in weather balloons rather than hydrogen gas which is highly combustible.

    142. Hydrogen is not found in atmosphere because

    (1) it is highly inflammable
    (2) it is the lightest gas
    (3) it is absorbed by plants
    (4) it immediately combines with oxygen to form water
    Answer:
    142. (2) Hydrogen is a chemical element with symbol H and atomic number 1. With an average atomic weight of 1.00794 u (1.007825 u for hydrogen-1), hydrogen is the lightest element and its monatomic form (H1) is the most abundant chemical substance, constituting roughly 75% of the Universe’s baryonic mass. Nonremnant stars are mainly composed of hydrogen in its plasma state. 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 vapor, on average around 1%. Naturally occurring atomic hydrogen is rare on Earth because hydrogen readily forms covalent compounds with most elements and is present in the water molecule and in most organic compounds.

    143. Who discovered the atom bomb?

    (1) Madam Curie
    (2) Pierre Curie
    (3) Otto Hahn
    (4) Albert Einstein
    Answer:
    143. (3) Otto Hahn, (8 March, 1879 – 28 July, 1968) was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as “the father of nuclear chemistry”. On 15 November 1945 the Royal Swedish Academy of Sciences announced that Hahn had been awarded the 1944 Nobel Prize in Chemistry “for his discovery of the fission of heavy atomic nuclei.” Otto Hahn received many governmental honours and academic awards from all over the world for his scientific work. He was elected member or honorary member of 45 Academies and scientific societies (among them the Physical Society, the University College and the Royal Society in London (1957) and the Academies in Allahabad (India), Bangalore (India), Boston (USA), Bucharest, Copenhagen, Helsinki, Lisbon, Madrid, Rome, Stockholm, Vienna) and received 37 of the highest national and international orders and medals.

    144. Which one of the following organic compounds has fruity smell?

    (1) Alcohol 
    (2) Aldehyde
    (3) Ester 
    (4) Ether
    Answer:
    144. (3) Esters are common in organic chemistry and biological materials, and often have a characteristic pleasant, fruity odour. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many polymers. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are widespread in nature and are widely used in industry. In nature, fats are, in general, triesters derived from glycerol and fatty acids. Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries.

    145. What material is used to make electric heater coil ?

    (1) Copper 
    (2) Iron
    (3) Silver 
    (4) Nichrome
    Answer:
    145. (4) Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point of about 1400 degree C (2552 degree F). Due to its relatively high electrical resistivity and resistance to oxidation at high temperatures, it is widely used in electric heating elements, such as in hair dryers, electric ovens, soldering iron, toasters, and even electronic cigarettes. Typically, Nichrome is wound in coils to a certain electrical resistance, and current is passed through to produce heat.

    146. By-product obtained by soap industry is

    (1) Caustic soda
    (2) Glycerol
    (3) Naphthalene
    (4) Caustic potash
    Answer:
    146. (2) Glycerol forms the backbone of triglycerides, and is chiefly produced by saponification of fats as a byproduct of soap-making. It is also a byproduct of the production of biodiesel via transesterification. This form of crude glycerin is often dark in appearance with a thick, syrup-like consistency. Triglycerides are treated with an alcohol such as ethanol with catalytic base to give ethyl esters of fatty acids and glycerol . Glycerol (or glycerine, glycerin) is a simple polyol compound. It is a colourless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids known as triglycerides. Glycerol is sweettasting and of low toxicity.

    147. Polythene is polymer of

    (1) Ethylene 
    (2) Propylene
    (3) Acetylene 
    (4) Aniline
    Answer:
    147. (1) The ingredient or monomer is ethylene (IUPAC name ethene). It has the formula C2H4, consisting of a pair of CH2 groups connected by a double bond. Because the catalysts are highly reactive, the ethylene must be of high purity. Typical specifications are <5 ppm for water, oxygen, as well as other alkenes. Acceptable contaminants include N 2, ethane (common precursor to ethylene), and methane. Ethylene is usually produced from petrochemical sources, but also is generated by
    dehydration of ethanol. Polyethylene (abbreviated PE) or polythene (IUPAC name polyethene or poly
    (methylene)) is the most common plastic. Its primary use is within packaging (plastic bag, plastic films,
    geomembranes, containers including bottles, etc.).

    148. For determination of the age of which among the following is carbon dating method used ?

    (1) Fossils 
    (2) Rocks
    (3) Trees 
    (4) 1& 2 above
    Answer:
    148. (4) Radiocarbon dating (usually referred to as simply carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e., uncalibrated, radiocarbon ages are usually reported in radiocarbon years “Before Present” (BP), with “present” defined as CE 1950. Such raw ages can be calibrated to give calendar dates. One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites. When plants fix atmospheric carbon dioxide (CO2) into organic matter during photosynthesis they incorporate a quantity of 14C that approximately matches the level of this isotope in the atmosphere. After plants die or they are consumed by other organisms (for example, by humans or other animals), the accumulation of 14C
    fraction stops and the material declines at a fixed exponential rate due to the radioactive decay of 14C.

    149. A substance which readily forms colloidal solution in contact with water is called

    (1) Extrinsic colloid
    (2) Associated colloid
    (3) Hydrophobic colloid
    (4) Hydrophilic colloid
    Answer:
    149. (4) A colloidal dispersion in which the dispersed particles are more or less liquid and exert a certain attraction on and absorb a certain quantity of the fluid in which they are suspended is called as hydrophilic colloid. Molecules of a hydrophilic colloid have an affinity for water molecules and when dispersed in water become hydrated. Hydrated colloids swell and increase the viscosity of the system, thereby improving stability by reducing the interaction between particles and their tendency to settle. They may also possess a net surface electrical charge. The charge sign depends on the chemical properties of the colloid and the pH of the system. The presence of a surface charge produces repulsion of the charged particles and thus reduces the likelihood that the particles will adhere to one another and settle. Some examples of hydrophilic colloids used in pharmacy are acacia, methylcellulose, and proteins, such as gelatin and albumin.

    150. When formaldehyde and potassium hydroxide are heated, we get

    (1) Acetylene
    (2) Methyl alcohol
    (3) Methane
    (4) Ethyl formate
    Answer:
    150. (2) When formaldehyde and potassium hydroxide are heated,we get methyl alcohol and formic acid. it is cannizarroo reaction. The Cannizzaro reaction, named after its discoverer Stanislao Cannizzaro, is a chemical reaction that involves the base-induced disproportionation of an aldehyde. Cannizzaro first accomplished this transformation in 1853, when he obtained benzyl alcohol and potassium benzoate from the treatment of benzaldehyde with potash (potassium carbonate). More typically, the reaction would be conducted with sodium or potassium hydroxide. The oxidation product is a salt of a carboxylic acid and the reduction product is an alcohol.

    151. When conc. H2SO4 is added to dry KNO3, brown fumes are evolved. These fumes are due to

    (1) SO3 
    (2) SO2
    (3) NO2 
    (4) N2O
    Answer:
    151. (3) when concentrated hydrosulphuric acid is added to dry potassium nitrate brown fumes are evolved and these fumes are evolved due to the formation of nitrogen dioxide. Nitrogen dioxide is the chemical compound with the formula NO2. It is one of several nitrogen oxides. NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odour and is a prominent air pollutant. Nitrogen dioxide is a paramagnetic and bent molecule.

    152. The polymer used in making plastic crockery is

    (1) Decron 
    (2) Nylon
    (3) Bakelite 
    (4) Melamine
    Answer:
    152. (4) Melamine-formaldehyde resin or melamine is used in the manufacture of plastic crockery. Melamine resin or melamine formaldehyde (also shortened to melamine) is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization. Melamine resin is often used in kitchen utensils and plates (such as Melmac). Melamine resin utensils and bowls are not microwave safe. As with all thermosetting materials, melamine resin cannot be melted and, therefore, cannot be recycled through melting.

    153. Vulcanization of rubber is carried out by adding

    (1) Sulphur 
    (2) Carbon
    (3) Ozone 
    (4) Phosphorus
    Answer:
    153. (1) Vulcanization is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent “curatives” or “accelerators”. These additives modify the polymer by forming crosslinks (bridges) between individual polymer chains. Vulcanized materials are less sticky and have superior mechanical properties. A vast array of products are made with vulcanized rubber including tires, shoe soles, hoses, and hockey pucks. The process is named after Vulcan, Roman god of fire. Hard vulcanized rubber is sometimes sold under the brand names ebonite or vulcanite, and is used to make hard articles such as bowling balls and saxophone
    mouth pieces.

    154. Which of the following is used in dating archaeological findings ?

    (1)92U235 
    (2)6C14
    (3)3H1 
    (4)8O18
    Answer:
    154. (2) Radiocarbon dating (usually referred to as simply carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. Raw, i.e., uncalibrated, radiocarbon ages are usually reported in radiocarbon years “Before Present” (BP), with “present” defined as CE 1950. Such raw ages can be calibrated to give calendar dates. One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.

    155. Preparation of ‘Dalda or Vanaspati’ ghee from vegetable oil utilizes the following process :

    (1) Hydrolysis 
    (2)Oxidation
    (3) Hydrogenation
    (4) Ozonolysis
    Answer:
    155. (3) The largest scale application of hydrogenation is for the processing of vegetable oils (fats to give margarine and related spreads and shortenings). Typical vegetable oils are derived from
    polyunsaturated fatty acids (containing more than one carbon-carbon double bonds). Their partial
    hydrogenation reduces most but not all, of these carbon-carbon double bonds. Hydrogenation converts
    liquid vegetable oils into solid or semi-solid fats, such as those present in margarine. Hydrogenation - to
    treat with hydrogen - is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, generally an alkene.

    156. Smoke is formed due to

    (1) solid dispersed in gas
    (2) solid dispresed in liquid
    (3) gas dispresed in solid
    (4) gas dispersed in gas
    Answer:
    156. (1) Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires (including stoves, candles, oil lamps, and fireplaces), but may also be used for pest control (cf. fumigation), communication (smoke signals), defensive and offensive capabilities in the military (smokescreen), cooking (smoked salmon), or smoking (tobacco, cannabis, etc.). Smoke inhalation is the primary cause
    of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and
    pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products.

    157. Which of the following chemicals is used in photography ?

    (1) Aluminium hydroxide
    (2) Silver bromide
    (3) Potassium nitrate
    (4) Sodium chloride
    Answer:
    157. (2) Silver bromide (AgBr), a soft, pale-yellow, water insoluble salt well known (along with other silver halides) for its unusual sensitivity to light. This property has allowed silver halides to become the basis of modern photographic materials. AgBr is widely used in photographic films and is believed by some to have been used for making the Shroud of Turin. The salt can be found naturally as the mineral bromargyrite (bromyrite). Photographic properties of silver halides (in particular AgBr) were a result of deviations from an ideal crystal structure. Factors such as crystal growth, impurities, and surface defects all contribute to affect concentrations of point ionic defects and electronic traps, which subsequently affect the sensitivity to light and allow for the formation of a latent image.

    158. What is the principal ore of aluminium ?

    (1) Dolomite 
    (2) Copper
    (3) Lignite 
    (4) Bauxite
    Answer:
    158. (4) 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 TiO2. 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. Lateritic bauxites (silicate bauxites) are distinguished from karst bauxite ores (carbonate bauxites). The early discovered carbonate bauxites occur predominantly in Europe and Jamaica above carbonate rocks (limestone and dolomite), where they were formed by lateritic weathering and residual accumulation of intercalated clays or by clay dissolution residues of the limestone.

    159. Which gas is used as fire extinguisher ?

    (1) Carbon dioxide
    (2) Carbon monoxide
    (3) Carbon suboxide
    (4) Sulphur dioxide
    Answer:
    159. (1) A fire extinguisher, flame extinguisher, or simply an extinguisher, is an active fire protection device used to extinguish or control small fires, often in emergency situations. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire. Cartridge-operated extinguishers contain the expellant gas (usually carbon dioxide) in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent. This type is not as common, used primarily in areas such as industrial facilities, where they receive higherthan-average use. They have the advantage of simple and prompt recharge, allowing an operator to discharge the extinguisher, recharge it, and return to the fire in a reasonable amount of time.

    160. Which one of the following is extensively used for sterilizing water ?

    (1) Bleaching powder
    (2) Alum
    (3) Borax powder
    (4) Soda powder
    Answer:
    160. (1) Bleaching powder is extensively used in sterilizing water. Calcium hypochlorite is a chemical compound with formula Ca(OCl)2. It is widely used for water treatment and as a bleaching agent (bleaching powder). This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). Calcium hypochlorite is a yellow white solid which has a strong smell of chlorine. It is not highly soluble in water, and is more preferably used in soft to medium-hard water. It has two forms: a dry form and a hydrated form. The hydrated form is safer to handle.


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