Chemistry GK Questions Quiz-29

Chemistry GK Questions Quiz-29

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

    561. The rusting of iron is a/an

    (1) physical change
    (2) electrochemical change
    (3) electrical change
    (4) None of the above
    Answer:
    561. (2) When iron is exposed to air and moisture, its surface gradually corroded and converted into a
    brown mass. The rusting of iron is due to the formation of hydrated ion. Rusting is an electro-chemical
    process.

    562. Sulphur dioxide level in the atmosphere can be reduced by using

    (1) more efficient car engines
    (2) catalytic converters in industry
    (3) static electricity to attract it in factory chimneys
    (4) low - sulphur fuels
    Answer:
    562. (4) The main source of sulphur dioxide into the atmosphere is from the burning of fossil fuels. Sulphur dioxide can damage plants and reduce crop yields.

    563. When a lead storage battery is discharged,

    (1) SO2 is evolved
    (2) Lead sulphate is consumed
    (3) Lead is formed
    (4) Sulphuric acid is consumed
    Answer:
    563. (4) Lead storage battery was invented by French physicist Gaston Plante in 1859. In the discharged
    state both the positive and negative plates become lead sulphate and the electrolyte loses much of its
    dissolved sulphuric acid and becomes primarily water.

    564. Benzene cannot undergo :

    (1) Substitution 
    (2) Addition
    (3) Elimination 
    (4) Oxidation
    Answer:
    564. (3) Benzene can not undergo Elimination reaction.

    565. Which among the following is found in chlorophyll ?

    (1) Ca2+ 
    (2) Mg2+
    (3) Fe2+ 
    (4) Al3+
    Answer:
    565. (2) Chlorophyll is the green pigment found in most plants, which is responsible for light absorption to provide energy by photosynthesis. Chlorophyll contains magnesium ion.

    566. The polymer obtained by the condensation of hexamethylene diamine and adipic acid is :

    (1) Nylon 66 
    (2) Terylene
    (3) Tollen’s 
    (4) Bakelite
    Answer:
    566. (1) Polymers are very high molecular mass substances each molecule of which consists of very large number of simple structural units joined together though covalent bonds in a regular fashion.
    Polymers whose repeating structural unit are derived from two or more types of monomer units are called copolymers. For examples, in case of nylon 66, the repeating structural unit is derived from two monomer units - hexamethylenediamine and adipic acid.

    567. Radioactive elements emit :

    (1) Radiowaves
    (2) Infrared waves
    (3) Ultraviolet waves
    (4) a, b and g radiations
    Answer:
    567. (4) The phenomenon of spontaneous emission of certain kinds of radiations by some elements is called radioactivity and the elements emitting such radiations are called radioactive elements. The
    nature of the radiations emitted from a radioactive substance was investigated by Rutherford in 1904
    by applying electric and magnetic fields to the radiations. It is observed that on applying the field, the rays emitted from the radioactive substances are separated in to three types, called a, b and g rays .

    568. Which one out of the following helps in burning ?

    (1) Oxygen
    (2) Carbon monoxide
    (3) Nitrogen
    (4) Carbon dioxide
    Answer:
    568. (1) Karl Scheele, the Swedish chemist, was the first to prepare oxygen by heating mercuric oxide in 1772. Joseph Priestley, the English chemist, also prepared oxygen in 1774 by focusing the sun’s rays with the help of a lens on mercuric oxide. Its elemental nature was, however, established by the French chemist, Lavoisier.

    569. In organic compounds, nitrogen is estimated by

    (1) Carius method
    (2) Victor-Meyer’s method
    (3) Liebig’s method
    (4) Dumas’ method
    Answer:
    569. (4) In Dumas’ method, a known quantity of nitrogen containing organic compound is heated strongly with excess of copper oxide in an atmosphere of carbon dioxide to produce free nitrogen in addition to carbon dioxide and water.

    570. The hottest part of the gas flame is known as

    (1) blue zone
    (2) non-luminous zone
    (3) luminous zone
    (4) dark zone
    Answer:
    570. (3) The hottest part of the gas flame is known as luminous zone.

    571. Silicon is a

    (1) Semiconductor
    (2) Insulator
    (3) Nonconductor
    (4) Conductor
    Answer:
    571. (1) Silicon is a chemical element with the symbol Si and its atomic number is 14. Over 90 percent of the Earth’s crust is composed of silicate minerals. Highly purified silicon is used in semiconductor electronics.

    572. The orientation of an atomic orbital is governed by

    (1) principal quantum number
    (2) magnetic quantum number
    (3) spin quantum number
    (4) azimuthal quantum number
    Answer:
    572. (2) Quantum numbers may be defined as a set of four numbers which give complete information about the electron in an atom, i.e., energy, orbital occupied, size, shape and orientation of that orbital and the direction of electron spin. Magnetic quantum number is required to explain the fact that when the source giving the line spectrum is placed in a magnetic field, each spectral line splits in to a number of lines. The magnetic quantum number tells the number of orientations which the orbitals present within the same sub-shell can take up.

    573. The percentage of oxygen in air is approximately

    (1) 100% 
    (2) 1%
    (3) 78% 
    (4) 21%
    Answer:
    573. (4) Composition of air
    Nitrogen : 78.08 percent
    Oxygen : 20.94 percent
    Argon : 0.93 percent
    Carbondioxdide : 0.03 percent
    Neon : 0.0018 percent
    Helium : 0.0005 percent
    Ozone : 0.00006 percent
    Hydrogen : 0.00005 percent

    574. What is the second largest component in milk ?

    (1) Fat
    (2) Minerals
    (3) Water 
    (4) Sugar
    Answer:
    574. (1) Components of Milk : Water (87 percent), Carbohydrate (4.9 percent), Fat (3.4 percent), Protein (3.3 percent), and so on.

    575. Bayer’s reagent is

    (1) Alkaline potassium permanganate
    (2) Acidified potassium permanganate
    (3) Hydrogen peroxide
    (4) Bromine water
    Answer:
    575. (1) Baeyer’s reagent is an alkaline solution of potassium permanganate, which is a powerful oxidant. It is used in organic chemistry as a qualitative test for the presence of unsaturation.

    576. The value of Avogadro Number is

    (1) 6.023 × 1022
    (2) 6.023 × 1023
    (3) 6.023 × 1024
    (4) 6.023 × 1025
    Answer:
    576. (2) In chemistry and physics, the Avogadro constant is defined as the number of constituent particles (usually atoms or molecules) in one mole of a given substance. It has dimensions of reciprocal mol and its value is equal to 6.023 ×1023.

    577. Choose the incorrect statement pertaining to organic compounds

    (1) They have low melting and boiling points
    (2) They do not dissolve in water
    (3) They are not easily combustible
    (4) They contain mainly carbon and hydrogen
    Answer:
    577. (3) Typical organic compounds are combustible by nature as they contain carbon. Organic compounds mostly consist of carbon, hydrogen, halogen, and phosphorus.

    578. The weight of 6.023 × 1022 atoms of carbon is

    (1) 12 gms 
    (2) 120 gms
    (3) 1.2 gms 
    (4) 0.12 gms
    Answer:
    578. (1) The number 6.023 ×1023 is known as Avogadro’s Number which is the number of atoms in 12g of the isotope carbon-12. 6.023 ×1023 carbon atoms weigh = 12 grams.

    579. If the sewage is fully oxidized, the nitrogen is in the form of

    (1) Nitrites 
    (2) Ammonia
    (3) Nitramines 
    (4) Nitrates
    Answer:
    579. (4) Oxidized forms of nitrogen include nitrite (NO2) and nitrate (NO3). Nitrogen mainly occurs in wastewater in this form. Because nitrite is easily oxidized to nitrate, nitrate is the compound predominantly found in groundwater and surface waters.

    580. Suspension particles have the size between

    (1) 10–2 and 10–4 cm
    (2) 10–5 and 10–7cm
    (3) 10–8 and l0-10 cm
    (4) 10–1 and 10–2 cm
    Answer:
    580. (1) Suspension particles have the size between 10–2and 10–4 cm.


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