Chemistry GK Questions Quiz-21

Chemistry GK Questions Quiz-21

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

    401. The natural resource, known as black gold is

    (1) coal 
    (2) lead
    (3) tin 
    (4) platinum
    Answer:
    401. (1) The term "coal is a black gold" is just a simple metaphor. Even today, we burn more coal than natural gas, more than nuclear, more than anything.

    402. This group of alumino-silicate minerals is widely used in making electrical insulators

    (1) Bauxite 
    (2) Chromite
    (3) Manganese 
    (4) Mica
    Answer:
    402. (4) Sheet mica is used principally in the electronic and electrical industries. Its usefulness in these
    applications is derived from its unique electrical and thermal insulating properties and its mechanical
    properties, which allow it to be cut, punched, stamped, and machined to close tolerances. Specifically, Mica is unusual in that it is a good electrical insulator at the same time as being a good thermal conductor.

    403. Which of the following is a renewable source of energy ?

    (1) Coal
    (2) Geothermal powder
    (3) Natural gas
    (4) Uranium
    Answer:
    403. (2) Geothermal electricity is electricity generated from geothermal energy. Geothermal power is considered to be sustainable because the heat extraction is small compared with the Earth's heat content.

    404. The acid which is secreted by the glands in the stomach wall is

    (1) sulphuric acid
    (2) hydrochloric acid
    (3) nitric acid
    (4) phosphoric acid
    Answer:
    404. (2) Gastric acid is a digestive fluid, formed in the stomach. It has a pH of 1.5 to 3.5 and is composed of hydrochloric acid (HCl) (around 0.5%, or 5000 parts per million), and large quantities of potassium chloride (KCl) and sodium chloride (NaCl). The acid plays a key role in digestion of proteins, by activating digestive enzymes, and making ingested proteins unravel so that digestive enzymes can break down the long chains of amino acids.

    405. Dry ice is

    (1) solid ammonia
    (2) solid sulphur dioxide
    (3) dry carbon dioxide gas
    (4) solid carbon dioxide
    Answer:
    405. (4) Dry ice is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue. It is useful for preserving frozen foods, ice cream, etc., where mechanical cooling is unavailable.

    406. Cement containing excess amount of lime

    (1) cracks during setting
    (2) becomes more strong
    (3) is slow setting
    (4) is quick setting
    Answer:
    406. (1) In cement almost entire amount of lime is present in combined state as calcium silicates and calcium aluminates. Cement containing excess amount of lime cracks during setting while cement containing less amount of lime is weak in strength. Setting of cement is an exothermic process.

    407. Which one of the following is a micro-element ?

    (1) Chlorine 
    (2) Hydrogen
    (3) Nitrogen 
    (4) Oxygen
    Answer:
    407. (1) In analytical chemistry, a trace element or microelement is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count or less than 100
    micrograms per gram. These are those elements essential for plant growth which are needed in only
    very small (micro). They are: boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn).

    408. Rock salt is a mineral containing

    (1) potassium 
    (2) magnesium
    (3) sodium 
    (4) iron
    Answer:
    408. (3) Halite, commonly known as rock salt, is the mineral form of sodium chloride (NaCl). Halite forms isometric crystals. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates.

    409. In a nuclear reactor the material use for absorbing neutrons is

    (1) zinc 
    (2) radium
    (3) lead 
    (4) cadmium
    Answer:
    409. (4) One isotope of cadmium, 113Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cut-off and transmits them otherwise. The cadmium cut-off is about 0.5 eV. Neutrons with energy below the cut-off are deemed slow neutrons, distinguishing them from intermediate and fast neutrons.

    410. Solder metal is an alloy of

    (1) lead and tin
    (2) lead and antimony
    (3) copper and zinc
    (4) copper and tin
    Answer:
    410. (1) A solder is a fusible metal alloy of tin and lead with a melting point or melting range of 90 to 450°C, used in a process called soldering where it is melted to join metallic surfaces. It is especially useful in electronics and plumbing.

    411. Ozone depletion in the atmosphere is mainly caused by

    (1) sulphur dioxide
    (2) nitrogen dioxide
    (3) hydrogen sulphide
    (4) chlorofluorocarbon
    Answer:
    411. (4) A chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, hydrogen and fluorine, produced as a volatile derivative of methane and ethane. They contribute to ozone depletion in the upper atmosphere.

    412. Which of the following metals occurs in free state ?

    (1) Copper 
    (2) Iron
    (3) Zinc 
    (4) Lead
    Answer:
    412. (4) A native metal is any metal that is found in its metallic form, either pure or as an alloy, in nature. Metals that can be found as native deposits singly and/or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, nickel, selenium, tantalum, tellurium, tin, titanium, and zinc, as well as two groups of metals: the gold group, and the platinum group. The gold group consists of gold, copper, lead, aluminium, mercury, and silver.

    413. Copper is refined by

    (1) roasting 
    (2) oxidation
    (3) electrolysis 
    (4) zone refining
    Answer:
    413. (1) Copper is refined by the method of roasting. In the roaster, the copper concentrate is partially oxidised to produce "calcine" and sulfur dioxide gas. In roasting, the ore or ore concentrate is treated with very hot air. This process is generally applied to sulphide minerals.

    414. Which one of the following is used as preservative for foodstuff ?

    (1) Sodium Benzoate
    (2) Picric acid
    (3) Glycerine
    (4) Sodium Chloride
    Answer:
    414. (1) Sodium benzoate is a preservative. It is bacteriostatic and fungistatic under acidic conditions.
    It is most widely used in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also used as a preservative in medicines and cosmetics.

    415. The element with highest first ionisation energy is

    (1) hydrogen 
    (2) helium
    (3) lithium 
    (4) sodium
    Answer:
    415. (2) The first ionisation energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+. The first first ionisation energy (in KJ per mole) of Hydrogen: around 1200; Helium: about 2500; Lithium: about 500; and Sodium: about 500.

    416. Carbon dioxide is

    (1) a reducing agent
    (2) an oxidising agent
    (3) a dehydrating agent
    (4) a bleaching agent
    Answer:
    416. (1) A good reducing agent must be able to donate electrons readily. This means that it must not have very much attraction for electrons. Carbon dioxide is just like any other oxide and can be reduced to its respective elements by applied energy. CO2+C ® 2CO.

    417. An atom of an element has atomic number 17 and mass number 36. The number of neutrons in its nucleus is

    (1) 17 
    (2) 19
    (3) 36 
    (4) 53
    Answer:
    417. (2) Mass Number= number of protons (atomic number) + number of neutrons. So as per the question, 36= number of neutrons + 17. Number of neutrons= 36 – 17= 19

    418. Seaweeds are important source of

    (1) fluorine 
    (2) chlorine
    (3) bromine 
    (4) iodine
    Answer:
    418. (4) Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant.

    419. The resources which can be used continuously, year-after -year are called

    (1) Biotic 
    (2) Abiotic
    (3) Non-renewable
    (4) Renewable
    Answer:
    419. (4) A renewable resource is a natural resource with the ability to reproduce through biological or natural processes and replenished with the passage of time. Renewable resources are part of our natural
    environment and form our eco-system.

    420. Refrigerators keep food unspoiled because

    (1) at its low temperature, bacteria and moulds are inactive
    (2) at its low temperature, the germs are killed
    (3) at its low temperature, the germs are frozen
    (4) it sterilises the food
    Answer:
    420. (1) Bacteria and moulds find conditions of low pH, moisture, or temperature and high salt or sugar
    unfavorable for their operation. This is the principle why refrigerators keep food unspoiled for a long time. Bacterial action is severely impaired at temperatures at or below 4 degree Celsius.


    यह भी देखे :




















    Post a Comment

    0 Comments