Chemistry GK Questions Quiz-26

Chemistry GK Questions Quiz-26

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

    501. Brine refers to :

    (1) Salt water 
    (2) Sweet water
    (3) Pure water 
    (4) Starch water
    Answer:
    501. (1) Brine is a solution of salt in water. In different contexts, brine may refer to salt solutions ranging from about 3.5% up to about 26%. Other levels of concentration are called in different names.

    502. The chemical substance present in bones and teeth is

    (1) Calcium phosphate
    (2) Calcium chloride
    (3) Calcium sulphate
    (4) Calcium borate
    Answer:
    502. (1) Seventy percent of bone consists of hydroxyapatite, a calcium phosphate mineral (known as bone mineral). Tooth enamel is composed of almost ninety percent hydroxylapatite.

    503. Maximum permissible concentration of copper in drinking water in mg/L is

    (1) 0.01 
    (2) 0.05
    (3) 1.0 
    (4) 2.0
    Answer:
    503. (3) In the first edition of the Guidelines for Drinking Water Quality, published in 1984, a guideline value of 1.0 mg/litre was established for copper, based on its laundry and other staining properties.

    504. Which one of the following is known as the ‘brown coal’ ?

    (1) Anthracite 
    (2) Bituminous
    (3) Coke 
    (4) Lignite
    Answer:
    504. (4) Lignite, often referred to as brown coal, is a soft brown fuel with characteristics that put it somewhere between coal and peat. It is considered the lowest rank of coal. It has a carbon content of around 25- 35%.

    505. The chief source of naphthalene is

    (1) Coal-tar 
    (2) Diesel
    (3) Charcoal 
    (4) Camphor
    Answer:
    505. (1) Naphthalene is derived from a kind of naphtha which is a broad term encompassing any volatile, flammable liquid hydrocarbon mixture, including coal tar.

    506. Which of the following is the best fuel in terms of energy released per gram of fuel?

    (1) Hydrogen 
    (2) Methane
    (3) Ethanol 
    (4) Butane
    Answer:
    506. (1) The amount of energy released increases with the number of bonds present in the chemical substance or fuel. That is because each bond has a certain amount of energy stored in it therefore the more bonds the more energy is stored and more energy is released if these bonds break through combustion. Theoretical values of energy released per gram of fuel (in joules/ gram) are: Hydrogen: 142.5 KJ/g; Methane: 55.6 KJ/ g; Ethanol: 29.7 KJ/g; Butane: 49.6KJ/g.

    507. One carat of diamond is equal to

    (1) 100 mg 
    (2) 150 mg
    (3) 200 mg 
    (4) 250 mg
    Answer:
    507. (3) One carat is equal to 200 milligrams, or in other words, a 5-carat stone weighs 1 gram. The weight of one carat is precisely 0.2 grams.

    508. Iron is extracted from

    (1) Cinnabar 
    (2) Haematite
    (3) Bauxite 
    (4) Dolomite
    Answer:
    508. (2) Haematite is mined as the main ore of iron. It is harder than pure iron, but much more brittle. It is coloured black to steel or silver-gray, brown to reddish brown, or red.

    509. Which of the following imparts a blue colour to glass ?

    (1) Cabalt oxide
    (2) Copper oxide
    (3) Iron oxide
    (4) Nickel oxide
    Answer:
    509. (1) The addition of oxides, sulfides, salts, and other compounds of different metals to molten glass at the time of manufacture adds colour to glass. The introduction of electrically charged ions which are
    evenly distributed in the glass during manufacture also gives glass a characteristic colour. Cobalt oxide:
    deep blue colour; copper oxide: turquoise; chromium: dark green to black; cadmium sulfide: deep yellow, etc.

    510. A matured mammalian cell without nucleus is

    (1) Lymphocyte
    (2) Erythrocyte
    (3) Spermatozoan
    (4) Oocyte
    Answer:
    510. (2) Mammalian erythrocytes are unique among the vertebrates as they are non-nucleated cells in their mature form. These cells have nuclei during early phases of erythropoiesis, but extrude them during development as they mature in order to provide more space for hemoglobin. In mammals, erythrocytes also lose all other cellular organelles such as their mitochondria, Golgi apparatus and endoplasmic reticulum.

    511. The most common cause of pollution of air is

    (1) Carbon dioxide
    (2) Carbon monoxide
    (3) Sulphur dioxide
    (4) Smoke
    Answer:
    511. (3) The most common sources of air pollution include particulates, ozone, nitrogen dioxide, and sulfur dioxide. The largest sources of SO2 emissions are from fossil fuel combustion at power plants (73%) and other industrial facilities (20%). Smaller sources of SO2 emissions include industrial processes such as extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment. It is linked with a number of adverse effects on the respiratory system.

    512. The process by which milk is converted to curd is called

    (1) Pasteurization
    (2) Vernalization
    (3) Fermentation
    (4) Retting
    Answer:
    512. (3) Curds are a dairy product obtained by curdling (coagulating) milk with rennet or an edible acidic substance such as lemon juice or vinegar, and then draining off the liquid portion. The increased acidity causes the milk proteins (casein) to tangle into solid masses, or curds. The remaining liquid, which contains only whey proteins, is the whey. In Asia, curds are essentially a vegetarian preparation using yeast to ferment the milk.

    513. The technique of calculating the age of fossil organisms is

    (1) Radiocarbon dating
    (2) Electroporation
    (3) Counting the annual rings
    (4) Micromanipulation
    Answer:
    513. (1) 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. The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949.

    514. Nitrogen forms a variety of compounds in all oxidation states ranging from

    (1) –3 to + 5 
    (2) –3 to + 3
    (3) –3 to + 4 
    (4) –3 to + 6
    Answer:
    514. (1) Nitrogen compounds are chemical compounds containing nitrogen ions. Nitrogen forms compounds with a wide range of oxidation states that range from -3 for the nitride ion to +5 in nitrates and nitric acid. +5 oxidation state compounds are strong oxidizing agents. -3 oxidation state compounds are weak reducing agents.

    515. The next higher homologue of C6H14 is

    (1) C7H14 
    (2) C7H12
    (3) C6H12 
    (4) C7H16
    Answer:
    515. (4) In chemistry, a homologous series is a series of compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group. C6H14 stands for Hexane which is an alkane with six carbon atoms. In the alkane homologous series, each member differs from the previous one by a CH2 group (or 14 atomic mass units). The CH2 group is called Methylene Group. So the higher homologue of Hexane is Heptane (C7H16).

    516. Which of the following is used as a moderator in nuclear reactors ?

    (1) Thorium
    (2) Graphite
    (3) Ordinary water
    (4) Radium
    Answer:
    516. (2) Graphite is used a moderator in nuclear reactors.

    517. Sodium vapour lamps glow with yellow colour. This is due to

    (1) sublimation of sodium to emit yellow colour
    (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
    (3) the low ionisation energy of sodium
    (4) its ability to absorb all other colours except yellow
    Answer:
    517. (2) Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.

    518. Philosopher’s wool is chemically

    (1) Aluminium oxide
    (2) Magnesium oxide
    (3) Zinc oxide
    (4) Calcium oxide
    Answer:
    518. (3) Philosopher’s Wool is chemically zinc oxide.

    519. Charcoal is used in water treatment as a/an

    (1) absorbent 
    (2) coagulant
    (3) solvent 
    (4) adsorbent
    Answer:
    519. (4) Charcoal is used in water treatment as adsorbent.

    520. The gas involved in Bhopal incident was

    (1) Hydrogen sulphide
    (2) Nitrogen dioxide
    (3) Methyl chloride
    (4) Methyl isocyanide
    Answer:
    520. (4) Methyl Isocyanide gas.


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