Chemistry GK Questions Quiz-32

Chemistry GK Questions Quiz-32

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

    621. The presence of Cobalt in Vitamin B12 was established for the first time by

    (1) Hydrolysis test
    (2) Spectroscopy
    (3) Borax-Bead test
    (4) Sodium Nitroprusside test
    Answer:
    621. (2) Atomic absorption spectroscopy is an analytical chemistry technique used for determining
    concentration of particular metal element and is widely used in pharmaceutics. It was used for the
    determination of cobalt in Vitamin B 12.

    622. Coating of solid waste with impervious material is known as

    (1) Encapsulation
    (2) Chemical fixation
    (3) Landfill
    (4) Capping
    Answer:
    622. (1) Containment of toxic or hazardous constituents in industrial solid wastes is currently being accomplished using: (i) coating grains of waste material with an inert and non-reactive impervious material (microencapsulation), and (ii) coating blocks of waste material with an inert, non-reactive impervious material (macroencapsulation).

    623. Ultraviolet rays can be used in water treatment as

    (1) Flocculator 
    (2) Precipitator
    (3) Hydrolyser 
    (4) Disinfectant
    Answer:
    623. (4) UV radiation can be an effective viricide and bactericide. Disinfection using UV radiation is
    commonly used in wastewater treatment applications and is finding an increased usage in drinking water treatment.

    624. The heaviest naturally occurring element is:

    (1) Mercury 
    (2) Polonium
    (3) Thorium 
    (4) Uranium
    Answer:
    624. (4) The heaviest element in terms of heaviest per a given number of atoms is the element with the highest atomic weight. This is the element with the largest number of protons, which is presently element 118, Ununoctium. Ununoctium is the heaviest element, but it is man-made. The heaviest naturally-occurring element is uranium (atomic number 92, atomic weight 238.0289).

    625. Sulphur dioxide bleaches colouring matter by :

    (1) Reduction
    (2) Dehydration
    (3) Decomposition
    (4) Oxidation
    Answer:
    625. (1) Sulphur dioxide gas exhibits bleaching properties in presence of moisture. It dissolves in water
    liberating nascent hydrogen. Nascent hydrogen removes oxygen atoms from the colouring matter
    (reduces colouring matter) and it loses its colour.

    626. Which of the following elements is not radio-active ?

    (1) Radium 
    (2) Plutonium
    (3) Zirconium 
    (4) Uranium
    Answer:
    626. (3) Zirconium is a lustrous, grey-white, strong transition metal that resembles titanium. Zirconium is mainly used as a refractory and opacifier, although it is used in small amounts as an alloying agent for its strong resistance to corrosion.

    627. Gypsum is used for improvement of:

    (1) Alkaline soils 
    (2) Saline soils
    (3) Podsols 
    (4) Acidic soils
    Answer:
    627. (2) Gypsum is calcium sulfate which is essential to the sustainability of most irrigated soils. Irrigated land eventually leads to sodicity and salinity unless extreme care is taken. It improves sodic (saline) soils by removing sodium from the soil and replacing it with calcium.

    628. Spontaneous change is one in there is:

    (1) A lowering of entropy
    (2) A lowering of free energy
    (3) Increase in free energy
    (4) An increase in Internal energy
    Answer:
    628. (2) Entropy and enthalpy together make a new quantity, the Free Energy which, under conditions of constant temperature and pressure, determines the direction of spontaneous change. All spontaneous processes have a negative change in free energy.

    629. Heating of a ore below its melting point in the absence of air is known as

    (1) Refining 
    (2) Calcination
    (3) Roasting 
    (4) Smelting
    Answer:
    629. (2) Calcination involves simple decomposition of ore on heating below its melting point usually in absence of air to produce new compounds having higher percentage of metal as well as removing the moisture, organic matter and volatile impurities. Calcination makes the ore porous.

    630. The most electronegative element among the following is

    (1) Fluorine 
    (2) Sodium
    (3) Chlorine 
    (4) Oxygen
    Answer:
    630. (1) Electronegativity of the elements using the Pauling Scale is as follows: Fluorine: 3.98, Oxygen: 3.44, Chlorine: 3.16, and Sodium: 0.93. Electronegativity increases down the group and decreases down the period.

    631. Mark the compound which possesses ionic, covalent and coordinate bonds.

    (1) NH4Cl 
    (2) SO3
    (3) SO2 
    (4) H2O
    Answer:
    631. (1) Ammonium chloride (NH4Cl) is generally considered as an ionic compound but this compound has three different types of bond. There is ionic bond between NH4+ ion and Cl– ion. There are N-H covalent bonds. The formation of NH4+ from NH3 is sometimes described as the formation of a coordinate bond between NH3 and H+ , however once the bond is formed there is no difference between the four N-H bonds, NH4+ has a tetrahedral structure.

    632. The depletion of Ozone layer is mainly due to

    (1) Volcanic eruptions
    (2) Aviation fuels
    (3) Radioactive rays
    (4) Chlorofluorocarbons
    Answer:
    632. (4) Chlorofluorocarbons (CFCs) and other halogenated ozone depleting substances (ODS) are mainly responsible for man-made chemical ozone depletion. Chlorofluorocarbon (CFC) is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane.

    633. A nibble is equal to_____ bits.

    (1) 32 
    (2) 4
    (3) 8 
    (4) 16
    Answer:
    633. (2) In computing, a nibble is a four-bit aggregation, or half an octet. A nibble contains 4 bits.

    634. The non-metal found in the liquid state is

    (1) bromine 
    (2) nitrogen
    (3) fluorine 
    (4) chlorine
    Answer:
    634. (1) Bromine belongs to the halogen group. It is the only non-metal element that is in a liquid form at room temperature. At room temperature it is a reddish brown fuming liquid with an unpleasant chlorine like smell.

    635. Ionisation energy of nitrogen is greater than that of oxygen because nitrogen has

    (1) high bond dissociation energy
    (2) smaller atomic radius
    (3) stable half filled 2p sub level
    (4) high nuclear charge
    Answer:
    635. (3) Ionization energy is a measure of the ease in which atoms lose electrons and become positive ions. The 2s222p3 configuration in Nitrogen is more stable than 2s22p4 due to half filled p-sublevel. Hence nitrogen, N atom has greater ionization energy than oxygen, O atom.

    636. Sulphuric acid is

    (1) monobasic 
    (2) dibasic
    (3) tribasic 
    (4) tetrabasic
    Answer:
    636. (2) An example of a dibasic acid is sulphuric acid H2SO4. Dibasic acids yield two free hydrogen ions in solution for each molecule of acid ionized.H2SO4 ® 2H+ + SO42–

    637. Which one of the following group of gases contribute to the “Green House Effect”?

    (1) Carbon dioxide and Methane
    (2) Ammonia and Ozone
    (3) Carbon monoxide and Sulphur dioxide
    (4) Carbon tetraflouride and Nitrous oxide
    Answer:
    637. (1) The primary greenhouse gases in the Earth’s atmosphere are water vapour, carbon dioxide,
    methane, nitrous oxide, and ozone. When ranked by their direct contribution to the greenhouse effect, the most important are: Water vapour and clouds: 36-72 %, Carbon Dioxide: 9-26 %, Methane: 4-9 % and Ozone: 3-7 %.

    638. The gas used to extinguish fire is

    (1) Neon 
    (2) Nitrogen
    (3) Carbon dioxide
    (4) Carbon monoxide
    Answer:
    638. (4) Fires require these 3 things: a fuel (a hydrocarbon, which is a compound containing only carbon and hydrogen), a source of oxygen, and heat. Carbon Dioxide is most commonly used to extinguish fire as it displaces oxygen, thus choking the very source of a fire.

    639. An alloy used in making heating elements for electric heating device is

    (1) Solder 
    (2) Alloy Steel
    (3) Nichrome 
    (4) German Silver
    Answer:
    639. (3) Nichrome is a mixture of chromium and nickel. Nichrome wire is a great conductor of electricity. Nichrome is used to make heating coils and other types of elements in household appliances.

    640. The degree of dissociation of an electrolyte depends on

    (1) dilution
    (2) impurities
    (3) atmospheric pressure
    (4) method of dissolution
    Answer:
    640. (1) The extent to which an electrolyte dissociates into ions is known as degree of dissociation or ionization and depends upon the following factors: (1) Nature of the electrolyte, (2) Temperature, (3) Dilution, (4) nature of the solvent, and (e) presence of other ions.


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