Chemistry GK Questions Quiz-23

Chemistry GK Questions Quiz-23

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

    441- A powerful eye irritant present in smog is

    (1) nitric oxide
    (2) sulphur dioxide
    (3) peroxyacetyl nitrate
    (4) carbon dioxide
    Answer:
    441. (3) Peroxyacetyl nitrate is a secondary pollutant present in photochemical smog. It is thermally
    unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas. It is a lachrymatory
    substance.

    442. The most important ore of lead is

    (1) Galena 
    (2) Magnetite
    (3) Pyrolusite 
    (4) Siderite
    Answer:
    442. (1) Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral. Galena is one of the most abundant and widely distributed sulfide minerals.

    443. When water itself combines chemically with some element or mineral it is called

    (1) Carbonation 
    (2) Desilication
    (3) Hydration 
    (4) Oxidation
    Answer:
    443. (3) When water combines chemically with other elements, the process is called hydration. In organic chemistry, a hydration reaction is a chemical reaction in which a hydroxyl group (–OH) and a hydrogen cation (an acidic proton) are added to the two carbon atoms bonded together in the carbon-carbon double bond which makes up an alkene functional group. The reaction usually runs in a strong acidic, aqueous solution. Hydration leaves the non-water component intact.

    444. The electronic configuration of an atom having atomic number ‘20’ is

    (1) 2, 8, 10 
    (2) 2, 6, 8, 4
    (3) 2, 8, 8, 2 
    (4) 2, 10, 8
    Answer:
    444. (3) Electrons occupy shells around the outside of an atom. There can be up to two electrons in the first shell, up to eight in the second and up to eight in the third. A calcium atom (Ca) has electron structure 2,8,8,2.

    445. The most reactive among the halogens is

    (1) Fluorine 
    (2) Chlorine
    (3) Bromine 
    (4) Iodine
    Answer:
    445. (1) Fluorine is one of the most reactive elements in existence, attacking otherwise inert materials such as glass, and forming compounds with the heavier noble gases. It is a corrosive and highly toxic gas. The reactivity of fluorine is such that if used or stored in laboratory glassware, it can react with glass in the presence of small amounts of water to form silicon tetrafluoride (SiF4).

    446. The major component in the LPG is

    (1) methane 
    (2) butane
    (3) ethane 
    (4) propane
    Answer:
    446. (2) Butanes are highly flammable, colourless, easily liquefied gases. When blended with propane and other hydrocarbons, it is referred to commercially as LPG, for liquified petroleum gas. It is used as a petrol component.

    447. KMnO4 can be used as a/an

    (1) insecticide
    (2) fertiliser
    (3) pesticide 
    (4) disinfectant
    Answer:
    447. (4) Potassium permanganate is an inorganic chemical compound with the formula KMnO4. As an oxidant, potassium permanganate can act as an antiseptic. For example, dilute solutions are used to treat canker sores (ulcers), disinfectant for the hands and treatment for mild pompholyx, dermatitis, and fungal infections of the hands or feet. It is used extensively in the water treatment industry.

    448. Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives

    (1) Copper at cathode and oxygen at anode.
    (2) Copper at anode and oxygen at cathode.
    (3) Copper at cathode and anodes dissolve to give copper.
    (4) Hydrogen at cathode and oxygen at anode.
    Answer:
    448. (1) Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode. Bubbles of gas (oxygen) are formed at the anode. Cathode reaction: Cu2+ + (aq) + 2e– ® Cu(s); and Anode reaction: 2H2O(l ) ® O2(g) + 4H+(aq) + 4e-

    449. Which of the inert gases can form compounds?

    (1) Helium 
    (2) Xenon
    (3) Krypton 
    (4) Argon
    Answer:
    449. (2) Xenon compounds are the most numerous of the noble gas compounds that have been formed. Most of them have the xenon atom in the oxidation state of +2, +4, +6, or +8 bonded to highly electronegative atoms such as fluorine or oxygen. Some of these compounds have found use in chemical synthesis as oxidizing agents.

    450. Burning pyrites ore gives out

    (1) Carbon dioxide gas
    (2) Sulphur dioxide gas
    (3) Nitrogen dioxide gas
    (4) Nitric oxide gas
    Answer:
    450. (2) The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS 2. Pyrite remains in commercial use for the production of sulfur dioxide, for use in such applications as the paper industry, and in the manufacture of sulfuric acid.

    451. Oxygen has (+) oxidation number only in

    (1) OF2 
    (2) Cl2O
    (3) H2O 
    (4) N2O
    Answer:
    451. (1) In case of F2O, oxygen is not the most electronegative element. The fluorine is more
    electronegative and has an oxidation state of -1. In this case, the oxygen has an oxidation state of +2.

    452. Which one of the following elements is used in the manufacture of fertilizers ?

    (1) Fluorine 
    (2) Potassium
    (3) Lead 
    (4) Aluminium
    Answer:
    452. (2) Nitrogen, phosphorus and potassium are the three most common bases of fertilizers. Potash can be used to make potassium (K) fertilizers. All commercial potash deposits come originally from marine deposits and are often buried deep in the earth.

    453. Natural rubber is the polymer of :

    (1) Isoprene 
    (2) Styrene
    (3) Butadiene 
    (4) Ethylene
    Answer:
    453. (1) Isoprene was first isolated by thermal decomposition of natural rubber. About 95% of
    isoprene production is used to produce cis-1,4- polyisoprene—a synthetic version of natural rubber.

    454. In addition to hydrogen, the other abundant element present on Sun’s surface is

    (1) Helium 
    (2) Neon
    (3) Argon 
    (4) Oxygen
    Answer:
    454. (1) The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass. The Sun inherited its chemical composition from the interstellar medium out of which it formed: the hydrogen and helium in the Sun were produced by Big Bang nucleosynthesis.

    455. Which of the following is the major constituent of LPG?

    (1) Methane 
    (2) Ethane
    (3) Propane 
    (4) Butane
    Answer:
    455. (4) Butanes are highly flammable, colourless, easily liquefied gases. When blended with propane and other hydrocarbons, it is referred to commercially as LPG, for liquefied petroleum gas.

    456. Ozone layer is present in

    (1) Troposphere
    (2) Ionosphere
    (3) Stratosphere
    (4) Exosphere
    Answer:
    456. (3) The ozone layer is mainly found in the lower portion of the stratosphere from approximately 20 to 30 kilometres above Earth, though the thickness varies seasonally and geographically. Generally, it is smaller near the equator and larger towards the poles. It also varies with season, being in general thicker during the spring and thinner during the autumn in the northern hemisphere.

    457. An electric iron has a heating element made of :

    (1) Copper 
    (2) Tungsten
    (3) Nichrome 
    (4) Zinc
    Answer:
    457. (3) Nichrome is used in electric iron because it has high resistance and it is stable in air when hot.
    Nichrome wire forms a protective layer of chromium oxide. Chemically it is quite stable and does not
    combine with other atmospheric gases even in high temperature.

    458. The process of covering water pipes made of Iron with Zinc layer to prevent corrosion is called :

    (1) Zinc plating
    (2) Alloy formation
    (3) Vulcanization
    (4) Galvanization
    Answer:
    458. (4) Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting.

    459. The particle required to continue the chain process of Uranium fission is :

    (1) Electron 
    (2) Proton
    (3) Neutron 
    (4) Positron
    Answer:
    459. (3) Fission as encountered in the modern world is usually a deliberately produced man-made nuclear reaction induced by a neutron. The nuclear fuels undergo fission when struck by fission neutrons, and in turn emit neutrons when they break apart. This makes possible a self-sustaining nuclear chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon.

    460. Which of the following is used to increase the anti-knocking property of petrol ?

    (1) Tetramethyl lead
    (2) Tetraethyl lead
    (3) Trimethyl lead
    (4) Triethyl lead
    Answer:
    460. (2) An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which ignition occurs. Tetraethyllead was admixed with gasoline (petrol) beginning in the 1920s as an inexpensive octane booster which allowed engine compression to be raised substantially, which in turn increased vehicle performance and fuel economy.


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