Chemistry GK Questions Quiz-36

Chemistry GK Questions Quiz-36

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

    701. Which of the following is very reactive and kept in kerosene?

    (1) Sodium 
    (2) Potassium
    (3) Iodine 
    (4) Bromine
    Answer:
    701. (1) Sodium is a very reactive metal. It reacts vigorously with oxygen and water. A lot of heat is generated in this process. Therefore, it is stored in kerosene to avoid contacts between either atmospheric oxygen or water.

    702. In the periodic table of elements, on moving from left to right across a period, the atomic radius

    (1) decreases
    (2) increases
    (3) remains unchanged
    (4) does not follow a definite pattern
    Answer:
    702. (1) The atomic radius is the distance from the atomic nucleus to the outermost stable electron orbital in an atom that is at equilibrium. It tends to decrease across a period from left to right. It usually increases while going down a group due to the addition of a new energy level (shell).

    703. Vulcanized rubber contains sulphur

    (1) 2% 
    (2) 3-5%
    (3) 7-9% 
    (4) 10-15%
    Answer:
    703. (2) A vulcanized flexible tyre rubber contains about 3 –5% of sulphur whereas hard rubber (ebonite) contains about 32% of sulphur. The stiffness of vulcanized rubber depends on the amount of sulphur added.

    704. Which of the following is a metallic ore ?

    (1) Mica 
    (2) Quartz
    (3) Feldspar 
    (4) Galena
    Answer:
    704. (4) Galena is the most abundant lead mineral. It is a metallic, lead-gray mineral with cubic cleavage and a distinctly high density. It belongs to the octahedral sulfide group of minerals with metal ions in octahedral positions.

    705. The moderator used in a nuclear reactor is

    (1) Uranium
    (2) Radium
    (3) Ordinary water
    (4) Graphite
    Answer:
    705. (3) Light water (ordinary water) is used as the moderator in U.S. reactors as well as the cooling agent. It acts as the means by which heat is removed to produce steam for turning the turbines of the electric generators.

    706. The chemical name of “Plaster of Paris” commonly used for setting broken bones is

    (1) Calcium nitrate
    (2) Calcium sulphate
    (3) Calcium carbonate
    (4) Calcium chloride
    Answer:
    706. (2) Plaster of Paris is the common name of Calcium Sulphate hemihydrate, with chemical formula:
    CaSO 4.1/2H2O. Plaster of Paris is produced by heating gypsum to about 150°C.

    707. The apparatus used to test acidity of aqueous solution is

    (1) pH meter 
    (2) Ammeter
    (3) Hygrometer
    (4) Acidmeter
    Answer:
    707. (1) A pH meter is an electronic device used for measuring the pH (acidity or alkalinity) of a liquid. A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading.

    708. Chemical formula of washing soda is

    (1) Na2SO4.10H2O
    (2) NaHCO3
    (3) Na2CO3.10H2O
    (4) Ca(OH)2
    Answer:
    708. (3) Washing Soda is essentially Sodium Carbonate, a sodium salt of carbonic acid (soluble in water). The molecular formula of washing soda is Na2CO3.10H2O. It is used as an agent to soften hard water. It reacts with the calcium and magnesium bonds present in the water, enabling the detergent to work.

    709. Hydrochloric acid is also known as

    (1) Galic acid
    (2) Picric acid
    (3) Muriatic acid
    (4) Chloric acid
    Answer:
    709. (3) Hydrochloric acid was historically called acidum salis, muriatic acid, and spirits of salt because it was produced from rock salt and green vitriol and later from the chemically similar substances common salt and sulfuric acid. Hydrochloric acid is found naturally in gastric acid.

    710. The inert gas used as beacon light is

    (1) Kr 
    (2) Ar
    (3) He 
    (4) Ne
    Answer:
    710. (4)Neon is used in neon discharge lamps and advertising signs because the neon lights are visible from long distances. Since the light of neon signs has a better penetrating power through fog and mist, the neon signs are also used in beacon lights for the safety of air and sea navigation.

    711. The chemical name of baking soda is

    (1) Sodium carbonate
    (2) Sodium bicarbonate
    (3) Sodium chloride
    (4) Sodium nitrate
    Answer:
    711. (2) Sodium bicarbonate (NaHCO3) is also known as baking soda. It is a chemical leavening agent which is added to baked goods before cooking to produce carbon dioxide and cause them to ‘rise’.

    712. Chemical name of common salt is

    (1) Sodium Chloride
    (2) Sodium Bicarbonate
    (3) Sodium
    (4) Sodium Oxide
    Answer:
    712. (1) Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the chemical formula NaCl, representing equal proportions of sodium and chlorine. In the form of table salt, it is commonly used as a condiment and food preservative.

    713. Which one of the following mineral does not contain oxygen ?

    (1) Haematite 
    (2) Bauxite
    (3) Cryolite 
    (4) Calcite
    Answer:
    713. (3) Cryolite (Na3AlF6, sodium hexafluoroaluminate) does not contain oxygen. It occurs as glassy, colorless, white-reddish to gray-black prismatic monoclinic crystals. Cryolite is used as an insecticide and a pesticide. It is also used to give fireworks a yellow color. 

    714. A non–electronic conductor is

    (1) Iron
    (2) Gas Carbon
    (3) Copper Sulphate
    (4) Mercury
    Answer:
    714. (*) Either the wording of the question is wrong or it doesn’t have a correct option. A non-conductor is a substance which does not allow the passage of electricity. As a general rule, all metals (Iron, Mercury, etc) are good conductors. Nonmetals are non-conductors, except for carbon in the form of graphite and the gas carbon. Copper Sulphate is a good electrolyte (a liquid which allows the passage of electricity. So all the options given in the question are good electrical conductors.

    715. Which of the following will replace hydrogen from acids to form salts ?

    (1) S 
    (2) Na
    (3) Ag 
    (4) P
    Answer:
    715. (2) All acids contain hydrogen atom (s). Dilute acids react with some metals such as Sodium, Potassium, Calcium, iron, etc to form salts. Sodium replaces two hydrogen atoms from Sulfuric acid (H2SO4) to form a normal salt, Sodium Sulphate (Na2SO4). If only one atom of hydrogen is replaced by sodium, it forms an acid salt, Sodium Hydrogen Sulphate (NaHSO4).

    716. Which of the following metals has least melting point ?

    (1) Gold 
    (2) Silver
    (3) Mercury 
    (4) Copper
    Answer:
    716. (3) The melting point of the given metals (in Celsius) are:- Gold: 1063; Silver: 961;Copper: 1083; Mercury: -38.86. Mercury is the only elemental metal known to melt at a generally cold temperature.

    717. The gas produced in marshy places due to decomposition of vegetation is

    (1) Carbon monoxide
    (2) Carbon dioxide
    (3) Sulphur dioxide
    (4) Methane
    Answer:
    717. (4)Methane gas is a hydrocarbon gas largely composed of methane formed when organic material or vegetation decays in the absence of air. Naturally occurring methane is mainly produced by the process of methanogenesis. It is also known as Swamp Gas.

    718. The chemical name of ‘‘Hypo’’ commonly used in photography is

    (1) Sodium thiosulphate
    (2) Silver nitrate
    (3) Sodium nitrate
    (4) Silver iodide
    Answer:
    718. (1) An emulsion of sodium thiosulfate is called hypo by photographers. It is used to stop development of exposed film. Thiosulfate converts undeveloped silver bromide grains in the film into water-soluble silver thiosulfate complexes that can be removed when the film is washed.

    719. Carborundum is another name of

    (1) Silicon carbide
    (2) Silicon oxide
    (3) Calcium carbide
    (4) Calcium oxide
    Answer:
    719. (1) Silicon carbide, also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive.

    720. Number of atoms present in one mole of a gas at STP is

    (1) 6.023 × 1020
    (2) 6.023 × 1023
    (3) 6.023 × 10–23
    (4) 6.023 × 10–20
    Answer:
    720. (2) A mole of a gas is the amount of a substance containing 6.023 x 1023 atoms. This is known as
    Avogadro’s number. 1 mole contains the same number of particles as there are in 12 g of carbon-12
    atoms by definition. 12 g of carbon-12 atoms = 6.022 x 1023 carbon atoms.


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