Chemistry GK Questions Quiz-47

Chemistry GK Questions Quiz-47

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

    921. Two electrons in an orbital are differentiated by which of the following ?

    (1) Magnetic quantum number
    (2) Spin quantum number
    (3) Principal quantum number
    (4) Azimuthal quantum number
    Answer:
    921. (2) Spin quantum number is the is the fourth quantum number that differentiates two electrons in the same orbital. The Pauli exclusion principle states that “no two electrons in an atom can have the same four quantum numbers. This means that no two electrons can have the same state in an atom. Each electron must have a different spin or occupy a different shell from any other.

    922. The most abundant element in the earth’s atmosphere is

    (1) Argon 
    (2) Nitrogen
    (3) Oxygen 
    (4) Krypton
    Answer:
    922. (2)The most abundant gas in the Earth’s atmosphere is nitrogen. Nitrogen makes up 78 percent of the Earth’s atmosphere, and it is a permanent gas, which means that its percentage does not change on a daily basis. The rest of the atmosphere is made up of 21 percent oxygen, 0.9 percent argon and 0.1 percent trace gases.

    923. Chemical composition of cement is

    (1) Limestone and Clay
    (2) Limestone, Clay and Gypsum
    (3) Limestone and Gypsum
    (4) Clay and Gypsum
    Answer:
    923. (2)The two important raw materials used for the preparation of cement are :
    l Limestone : The chemical formula of limestone is CaCO3 and it is used in the manufacture of cement
    just to provide CaO.
    l Clay : Clay is hydrated aluminium silicate and iron
    (iii) oxide having chemical formula Al2O3SiO2Fe2O3.2H2O. Thus, clay consists of aluminium oxide (Al2O3), silicon dioxide (SiO2), and iron (iii) oxide (Fe2O3) along with water molecules. In addition of limestone and clay, gypsum is also used during preparation of cement. It is added into the cement to slow down the hardening of cement when water is added into it.

    924. Which of the following is also used as a Bio fertilizer?

    (1) Urea 
    (2) Ammonia
    (3) Uric Acid 
    (4) Nitrates
    Answer:
    924. (*) A Bio fertilizer is a substance which contains living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Rhizobium, Azotobacter, Azospirillum and blue green algae are traditionally used as Biofertilizers. Best Option : (2) Ammonia occupies an unique biochemical position being the only inorganic form of nitrogen that is incorporated into organic linkage and thus an obligate intermediate in the utilization of other inorganic sources.

    925. ____ is used for making vinegar.

    (1) Tartaric acid
    (2) Malic acid
    (3) Oxalic acid
    (4) Acetic acid
    Answer:
    925. (4) Vinegar is a liquid consisting mainly of acetic acid (CH3COOH) and water. The acetic acid is produced by the fermentation of ethanol by acetic acid bacteria. It is mainly used as a cooking ingredient.

    926. Major portion of the earth’s crust is mainly constituted by

    (1) Oxygen and Iron
    (2) Oxygen and Silicon
    (3) Silicon and Iron
    (4) Silicon and Aluminium
    Answer:
    926. (2)Oxygen is the most abundant element in the earth’s crust, comprising 46.6% or the crust by weight. Silicon 28%, aluminum 8.2%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium, 2.0%, and titanium 0.61% also comprise the crust. Given the abundance of oxygen and silicon, the silicates are the most abundant minerals in the earth’s crust.

    927. Cinnabar is an ore/mineral of

    (1) Lead
    (2) Manganese
    (3) Molybdenum
    (4) Mercury
    Answer:
    927. (4) Cinnabarrefers to the common bright scarlet to brick-red form of mercury sulfide (HgS) that is the most common source ore for refining elemental mercury. It is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments.

    928. Which among the following is not a characteristic of transition metals?

    (1) Tendency to gain electrons
    (2) Low electronegativity
    (3) Low ionization energy
    (4) Malleability
    Answer:
    928. (1) The transition metals have a tendency to lose electrons. Since the electrons in the highest energy level are actually on a lower principal energy number than the ones before them, this makes it relatively easy to lose some or all of their electrons to land in stable state. When these metals form ions, the 4s electrons are always lost first; so, they form only cations (positive ions).

    929. Ethylene is a ______ molecule.

    (1) polar 
    (2) ionic
    (3) covalent 
    (4) nonpolar
    Answer:
    929. (4) Ethylene (C2H4) is a nonpolar molecule. This is because, unlike a polar molecule, it has an even distribution of electrical charges. Since, the double bond is between two carbon atoms, there is no difference in the electronegativity. This is why, the shared pair of electrons come lie in between those to carbon atoms. As a result, ethylene is a non-polar and linear molecule.

    930. If water smells bad, then that odour can be removed by adding

    (1) alum
    (2) bleach
    (3) activated carbon
    (4) deactivated nitrogen
    Answer:
    930. (3) Adding powdered activated carbon to water or using of granular activated carbon (GAC) in the water filter can remove bad taste and foul odour. Powdered activated carbon (PAC) is the preferred method when the taste and odour is moderate and infrequent. Activated carbon works by a phenomenon called “Adsorption”, which is where the odour compound is trapped inside the activated carbon and retained, but the material doing the adsorption does not change size.

    931. The basic process taking place in nuclear reactors is

    (1) Radioactivity
    (2) Fission
    (3) Fusion
    (4) None of the above
    Answer:
    931. (2) A nuclear reactor produces and controls the release of energy from splitting the atoms of uranium, known as nuclear fission. When a fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it undergoes nuclear fission in which the heavy nucleus splits into two or more lighter nuclei. The fission process produces free neutrons and gamma photons, and releases a very large amount of energy.

    932. Malathion is a/an

    (1) insecticide 
    (2) fumigant
    (3) preservative 
    (4) pesticide
    Answer:
    932. (1) Malathion is an organophosphate (OP) insecticide that has been registered for use in the United States since 1956. It is widely used in agriculture, residential landscaping, public recreation areas, and in public health pest control programs such as mosquito eradication. It is of relatively low human toxicity.

    933. The working of a dry cell is based on

    (1) Decomposition reaction
    (2) Spontaneous oxidation-reduction reaction
    (3) Combination reaction
    (4) Electrolysis
    Answer:
    933. (4) A dry cell is a type of battery that uses a paste electrolyte, with only enough moisture to allow current to flow. It works in accordance with Faraday’s law of electrolysis. It consists of an outer case made of zinc (the negative electrode), a carbon rod in the center of the cell (the positive electrode), and the space between them is filled with an electrolyte paste. In operation the electrolyte, causes the electrons to flow and produce electricity.

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