Chemistry GK Questions Quiz-22

Chemistry GK Questions Quiz-22

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

    421. Which of the following elements is not present in stainless steel?

    (1) Iron 
    (2) Tungsten
    (3) Chromium
    (4) Nickel
    Answer:
    421. (2) Stainless steel is defined as a steel alloy of iron with a minimum of 10.5% to 11% chromium content by mass. There are different types of stainless steels: when nickel is added, for instance, the austenite structure of iron is stabilized. This crystal structure makes such steels virtually non-magnetic and less brittle at low temperatures.

    422. Select the one which is not a mixture :

    (1) Air 
    (2) Gasoline
    (3) LPG 
    (4) Distilled water
    Answer:
    422. (4) Water (H2O) is the most abundant compound on Earth's surface. Water is a compound because it contains oxygen and hydrogen which are chemically combined in proportion.

    423. When Hydrogen starts burning in air, it produces ?

    (1) Ammonia 
    (2) Water
    (3) Methane 
    (4) Carbonic Acid
    Answer:
    423. (2) Hydrogen burns in oxygen or air to form water. 2H2 + O2 ® 2H2O

    424. Mercury is a :

    (1) solid metal
    (2) liquid metal
    (3) solid non-metal
    (4) liquid non-metal
    Answer:
    424. (2) A heavy, silvery d-block element, Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine. With a freezing point of -38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.

    425. Spirit in contact with body gives cool sensation because it is :

    (1) liquid
    (2) transparent
    (3) highly volatile
    (4) a good conductor
    Answer:
    425. (3) Spirit is very volatile. So when it is exposed, it evaporates rapidly to the air if released into the
    environment, producing a cool effect.

    426. Taj Mahal is greatly affected due to :

    (1) Tourists
    (2) Acid rain
    (3) Deforestation
    (4) Sound pollution
    Answer:
    426. (2) When sulphur pollutants fall on to buildings made from limestone and sandstone they react with minerals in the stone to form a powdery substance that can be washed away by rain. This is known as acid rain. Famous buildings like the Statue of Liberty in New York, the Taj Mahal in India and St. Paul's Cathedral in London have all been damaged by this sort of air pollution.

    427. The unit of ionic product of water (Kw) is :

    (1) Mol2 let-1 
    (2) Mol2 let-2
    (3) Mol-1 let-2 
    (4) Mol-1 let-1
    Answer:
    427. (2) Like any other equilibrium constant, the value of Kw varies with temperature. Its value is usually taken to be 1.00 × 10–14 mol2 dm–6 or Mol2 lit–2 at room temperature. In fact, this is its value at a bit less than 25°C. At 250 C, Kw = 1.00 x 10–14 (mol/L)2.

    428. The most abundant constituent of atmospheric air is :

    (1) carbon 
    (2) hydrogen
    (3) oxygen 
    (4) nitrogen
    Answer:
    428. (4) Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases.

    429- Which mineral is the ore of aluminium ?

    (1) Haematite 
    (2) Bauxite
    (3) Magnetite 
    (4) Siderite
    Answer:
    429. (2) Bauxite is an aluminium ore and is the main source of aluminium. Approximately 70% to 80% of the world's dry bauxite production is processed first into alumina, and then into aluminium by electrolysis.

    430. Which gas is used for converting vegetable oils into saturated fats ?

    (1) H2 
    (2) O2
    (3) Cl2 
    (4) SO2
    Answer:
    430. (1) Hydrogenation - to treat with hydrogen - is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst. The largest scale application of hydrogenation is for the processing of vegetable oils (fats to give margarine and related spreads and shortenings). Typical vegetable oils are derived from polyunsaturated fatty acids (containing more than one carbon-carbon double bonds). Their partial hydrogenation reduces most but not all, of these carbon-carbon double bonds.

    431. Chemical name of bleaching powder is :

    (1) Calcium chlorate
    (2) Calcium hypochlorite
    (3) Calcium chloro hypochlorite
    (4) Calcium bi chloride
    Answer:
    431. (2) Calcium hypochlorite is a chemical compound with formula Ca(ClO)2. It is widely used for water treatment and as a bleaching agent. This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochlorite.

    432. Alcoholic (– OH) group can be identified by :

    (1) Tollen's Reagent Test
    (2) Esterification Test
    (3) FeCl3 Test
    (4) Ozonolysis Reaction
    Answer:
    432. (3) As phenol is an aromatic alcohol, so FeCl3 test is a test for alcohol and esterificaton test is also a test for alcohol. The ferric chloride test is used to determine the presence or absence of phenols in a given sample (for instance natural phenols in a plant extract).

    433. Pollutant from motor car exhaust that causes mental disease is

    (1) Lead 
    (2) NO2
    (3) SO2 
    (4) Hg
    Answer:
    433. (1) Lead poisoning is a medical condition caused by increased levels of the heavy metal lead in the body. Lead interferes with a variety of body processes and is toxic to many organs and tissues including the heart, bones, intestines, kidneys, and reproductive and nervous systems. It interferes with the development of the nervous system and is therefore particularly toxic to children.

    434. The total energy of revolving electron in an atom

    (1) cannot be negative
    (2) can have any value above zero
    (3) can never be positive
    (4) will always be positive
    Answer:
    434. (3) The total energy of a revolving electron in any orbit is the sum of its kinetic and potential energies. Energy of an electron at infinite distance from the nucleus is zero. As an electron approaches the nucleus, the electron attraction increases and the energy of electron decreases and thus becomes negative. Thus, it can never be positive.

    435- Conduction band electrons have more mobility than holes because they

    (1) are lighter
    (2) experience collision less frequently
    (3) have negative charge
    (4) need less energy to move them
    Answer:
    435. (2) When an electric field is applied, both the valence electrons and the free electrons move in the same direction. The hole direction is opposite to that of valence electron but the mobility is the same. Even for the same electric field, valence electrons cannot move as freely as the free electrons because its movement is restricted due to collisions. Therefore, the velocity of valence electrons is less compared to free electrons. In other words, the velocity of holes is less compared to free electrons. This means mobility is also less for a hole compared to free electron.

    436- The mass number of a nucleus is

    (1) always less than its atomic number
    (2) always more than its atomic number
    (3) always equal to its atomic number
    (4) sometimes more and somtimes equal to its atomic number
    Answer:
    436. (4) Mass number = protons or mass of electron (atomic number) + neutrons. So it is mostly greater than the atomic number. At best, it can be equal to the atomic number.

    437. Iodine can be separated from a mixture of Iodine and Potassium Chloride by

    (1) sedimentation
    (2) filtration
    (3) sublimation
    (4) distillation
    Answer:
    437. (3) Iodine is well known to sublime (change from solid to gas without becoming liquid inbetween) when heated. However sodium chloride has a melting point much higher than that of iodine. Therefore, a mixture of iodine and sodium chloride can be separated by using a sublimation apparatus, with solid iodine collected by condensation on a cold surface.

    438. Identify the metal which is non toxic in nature.

    (1) Chromium
    (2) Gold
    (3) Cadmium 
    (4) Cobalt
    Answer:
    438. (2) Toxic metals are metals that form poisonous soluble compounds and have no biological role, i.e. are not essential minerals, or are in the wrong form. Most often the definition includes at least cadmium, lead, mercury and the radioactive metals. Metals in an oxidation state abnormal to the body may also become toxic: chromium (III) is an essential trace element, but chromium(VI) is a carcinogen. Similarly, cobalt could also be toxic.

    439. The gas that usually causes explosions in coal mines is

    (1) Hydrogen
    (2) Carbon monoxide
    (3) Air 
    (4) Methane
    Answer:
    439. (4) Methane is extremely flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogens, and some halogencontaining compounds. Methane gas explosions are responsible for many deadly mining disasters.

    440. The chemical bahaviour of an atom depends upon

    (1) the number of protons in its nucleus
    (2) the number of neutrons in the nucleus
    (3) the number of electrons orbiting around the nucleus
    (4) the number of nucleons in the nucleus
    Answer:
    440. (3) The chemical behavior of an atom is determined by the number of electrons on its outer shell. As for the chemical bonding properties of the atom, the electron configuration determines how it will bond, with what it will bond, and in what ratio atoms will bond to form the 20,000,000 different substances on Earth.


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