McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 51. |
Soap is prepared by boiling caustic soda with – |
| A. | Alcohol |
| B. | Kerosene oil |
| C. | Glycerine |
| D. | Fats |
| Answer» D. Fats | |
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Explanation: The most basic kind of soap is made from cuastic soda and animal fat. The two are heated together, and then cooled. The process is called "saponification". In technical terms, saponification involves base (usually caustic soda NaOH) hydrolysis of triglyeerides which are esters of fatty acids, to form the sodium salt, of a carboxylate. |
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| 52. |
Bronze is an alloy of – |
| A. | Copper and Zinc |
| B. | Tin and Zinc |
| C. | Copper and Tin |
| D. | Iron and Zinc |
| Answer» C. Copper and Tin | |
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Explanation: Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and tough, and it was particularly significant in antiquity, so much that the Bronze Age was named after the metal. However, historical pieces were often made interchangeably of bronzes or brasses with different compositions, so modern museum and scholarly descriptions of older objects increasingly use the more inclusive term "copper alloy" instead. Historically the term latten was used for such alloys. |
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| 53. |
Which of the following elements is non- radioactive? |
| A. | Uranium |
| B. | Thorium |
| C. | Plutonium |
| D. | Zirconium |
| Answer» D. Zirconium | |
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Explanation: Zirconium is non-radioactive. It is a chemical element with the symbol Zr, atomic number 40 and atomic mass of 91.224. The name of zirconium is taken from the mineral zircon, the most important source of zirconium. It is a lustrous, grey-white, strong transition metal that resembles titanium. |
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| 54. |
The gas used for artificial fruit ripening of green fruit is – |
| A. | Ethylene |
| B. | Acetylene |
| C. | Ethane |
| D. | Methane |
| Answer» A. Ethylene | |
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Explanation: Ethylene can promote ripening in tomatoes, bananas, citrus, pineapples, dates, persimmons, pears, apples, melons, mangos, avocados, papayas and jujubes - a clear indication that the action of ethylene is general and widespread amongst a number of fruits. It is clear that ethylene is a ripening hormone - a chemical substance produced by fruits with the specific biological phenomenon of accelerating the normal process of fruit maturation and senescence. |
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| 55. |
Manganite is an ore/mineral of . |
| A. | Beryllium |
| B. | Chromium |
| C. | Manganese |
| D. | Copper |
| Answer» C. Manganese | |
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Explanation: Manganite is an ore mineral of manganese. As a manganese ore, it ranks after pyrolusite and romanechite. |
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| 56. |
The presence of which of the following salts in water causes corrosion in steam boilers? |
| A. | Sodium Chloride |
| B. | Magnesium Chloride |
| C. | Calcium bicarbonate |
| D. | Potassium bicarbonate |
| Answer» B. Magnesium Chloride | |
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Explanation: Magnesium chloride is the name for the chemical compound with the formula MgCl2 and its various hydrates MgCl2(H2O)x. These salts are typical ionic halides, being highly soluble in water. |
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| 57. |
The freezing point of fresh water is - |
| A. | 0°C |
| B. | 4°C |
| C. | 3°C |
| D. | 5 C |
| Answer» A. 0°C | |
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Explanation: Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 32 degrees Fahrenheit but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it. |
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| 58. |
is used for making vinegar. |
| A. | Tartaric acid |
| B. | Malic acid |
| C. | Oxalic acid |
| D. | Acetic acid |
| Answer» D. Acetic acid | |
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Explanation: Vinegar is a liquid consisting mainly of acetic acid (CH3COOH) and water. |
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| 59. |
Which of the following elements replaced eka-Aluminium in Mendeleev's Periodic Table? |
| A. | Scandium |
| B. | Gallium |
| C. | Titanium |
| D. | Germanium |
| Answer» B. Gallium | |
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Explanation: 0 |
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| 60. |
The most reactive among the halogens is - |
| A. | Fluorine |
| B. | Chlorine |
| C. | Bromine |
| D. | Iodine |
| Answer» A. Fluorine | |
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Explanation: As a general rule, fluorine is the most reactive halogen and astatine is the least reactive. All halogens form Group 1 salts with similar properties. |
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| 61. |
Which one of the following organic compounds has fruity smell? |
| A. | Alcohol |
| B. | Aldehyde |
| C. | Ester |
| D. | Ether |
| Answer» C. Ester | |
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Explanation: Esters are common in organic chemistry and biological materials, and often have a characteristic pleasant, fruity odour. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many polymers. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are widespread in nature and are widely used in industry. |
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| 62. |
What material is used to make electric heater coil? |
| A. | Copper |
| B. | Iron |
| C. | Silver |
| D. | Nichrome |
| Answer» D. Nichrome | |
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Explanation: Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point of about 1400 degree C (2552 degree F). |
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| 63. |
Which one of the following is a major green gas? |
| A. | Carbon dioxide |
| B. | Chloro fluorocarbon |
| C. | Carbon monoxide |
| D. | Freon |
| Answer» A. Carbon dioxide | |
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Explanation: A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. In the Solar System, the atmospheres of Venus, Mars, and Titan also contain gases that cause greenhouse effects. |
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| 64. |
Pasteurisation is the process in which milk is heated to – |
| A. | 60°C for 10 minutes |
| B. | 63° C for 20 minutes |
| C. | 63°C for 30 minutes |
| D. | 72°C for 10 minutes |
| Answer» C. 63°C for 30 minutes | |
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Explanation: Pasteurization for pasteurisation) is a process of heating a food, which is usually a liquid, to a specific temperature for a predefined length of time and then immediately cooling it after it is removed from the heat. This process slows spoilage due to microbial growth in thefood. Unlike sterilization, pasteurization is not intended to kill all micro-organisms in the food. Instead, it aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming the pasteurized product is stored as indicated and is consumed before its expiration date). |
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| 65. |
What is the maximum Water Vapour content in the atmosphere? |
| A. | 2 to 3 per cent |
| B. | 3 to 4 per cent |
| C. | 4 to 5 per cent |
| D. | 5 to 6 per cent |
| Answer» B. 3 to 4 per cent | |
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Explanation: The atmosphere of Earth is a layer of gases surrounding the planet. Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% |
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| 66. |
Steel contains – |
| A. | 0.1 - 2% carbon |
| B. | 5 - 10% carbon |
| C. | more than 10% carbon |
| D. | no carbon |
| Answer» A. 0.1 - 2% carbon | |
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Explanation: Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another. |
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| 67. |
The chemicals most commonly used for cloud seeding or artificial rainmaking' is/are |
| A. | Silver Iodide |
| B. | Sodium Chloride |
| C. | Dry ice or frozen carbon dioxide |
| D. | (4) All the above |
| Answer» A. Silver Iodide | |
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Explanation: Cloud seeding, a form of intentional weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the rnicrophysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports. The most common chemicals used for cloud seeding include silver iodide and dry ice (solid carbon dioxide). |
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| 68. |
The Refrigerant 'FREON' is – |
| A. | Calcium Tetra Fluoride |
| B. | Difluoro Dichloro Methane |
| C. | Fluorspar and Felspar |
| D. | Hydrofluosilicic Acid |
| Answer» B. Difluoro Dichloro Methane | |
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Explanation: Dichlorodifluorornethane (R-12), is a colourless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halornethane (CFC), used as a refrigrant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was banned in the United States along with many other countries in 1994 clue to concerns about damage to the ozone layer. It is soluble in many organic solvents. |
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| 69. |
is the number of shells for elements of the 3rd period. |
| A. | "2" |
| B. | "1" |
| C. | "0" |
| D. | "3" |
| Answer» C. "0" | |
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Explanation: The third period of the periodic table consists of the elements whose atoms has three shells occupied by electrons in its Ground State (when it is not excited or in a reaction). |
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| 70. |
Which one among the following polymers is used for making bullet-proof material? |
| A. | Polyvinyl chloride |
| B. | Polystyrene |
| C. | Polyethylene |
| D. | Polyamide |
| Answer» C. Polyethylene | |
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Explanation: A bullet-proof material is made of polyethylene. It is a higher grade of the plastic found in Tupperware. |
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| 71. |
The isotope of Uranium capable of sustaining chain reaction is - |
| A. | U-235 |
| B. | U-238 |
| C. | U-239 |
| D. | N.O.T. |
| Answer» A. U-235 | |
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Explanation: Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. |
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| 72. |
Conversion of chemical energy into electrical energy occurs in - |
| A. | Atomic bombs |
| B. | Dynamo |
| C. | A battery |
| D. | Electric heaters |
| Answer» C. A battery | |
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Explanation: A battery is a form of chemical energy that can be converted to electrical energy. it is a device consisting of one or more electrochemical cells which performs this action. The first battery (or "voltaic pile") was invented in 1800 by Alessandro Volta. |
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| 73. |
The fuel that is used in modern submarines is – |
| A. | Nuclear fuel |
| B. | Petrol |
| C. | Coal |
| D. | Diesel |
| Answer» A. Nuclear fuel | |
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Explanation: Nuclear power is now used in all large submarines, but due to the high cost and large size of nuclear reactors, smaller submarines still use diesel-electric propulsion. The ratio of larger to smaller submarines depends on strategic needs. The US Navy, drench Navy, and the British Royal Navy operate only nuclear submarines. |
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| 74. |
When lime juice is dropped on baking soda, brisk effervescence takes place because the gas evolved is - |
| A. | Hydrogen |
| B. | Oxygen |
| C. | Carbon dioxide |
| D. | All of them |
| Answer» C. Carbon dioxide | |
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Explanation: When baking soda and lemon juice are added together, the reaction of the two is an acid-based reaction because it involves an acid (citric acid in the lemon juice) reacting with a base (sodium bicarbonate, more commonly known as baking soda). Carbon dioxide, a gas, is produced by the reaction. |
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| 75. |
The basic chemical building block of natural rubber obtained from trees is – |
| A. | Isoprene |
| B. | Vinyl Chloride |
| C. | Acetylene |
| D. | Neoprene |
| Answer» A. Isoprene | |
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Explanation: Isoprene was first isolated by thermal decomposition of natural rubber. About 95% of isoprene production is used to produce cis-1,4- polyisoprene---a synthetic version of natural rubber. Natural rubber consists mainly of poly-cis-isoprene with a molecular weight of 100,000 to 1,000,000. |
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| 76. |
Hydrogen was discovered by - |
| A. | Cavendish |
| B. | Lavosier |
| C. | Rutherford |
| D. | Scheele |
| Answer» A. Cavendish | |
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Explanation: In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "flammable air". |
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| 77. |
Glass is a – |
| A. | pure solid |
| B. | supercooled liquid |
| C. | gel |
| D. | polymer |
| Answer» B. supercooled liquid | |
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Explanation: Glass is an amorphous (non- crystalline) solid material. Glasses are typically brittle and optically transparent. The standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. However, the term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. |
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| 78. |
Uranium eventually decays into a stable isotope of — |
| A. | Radium |
| B. | Thorium |
| C. | Lead |
| D. | Polonium |
| Answer» C. Lead | |
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Explanation: Natural uranium consists of three major isotopes: U238 (99.28% natural abundance), U235 (0.71%), and U234 (0.0054%). All three are radioactive, emitting alpha particles, with the exception that all three of these isotopes have small probabilities of undergoing spontaneous fission, rather than alpha emission. U23° is usually an alpha emitter (occasionally, it undergoes spontaneous fission), decaying through the "Uranium Series" ofnuclear decay, which has 18 members, all of which eventually decay into Pb206, by a variety of different decay paths. |
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| 79. |
The substance that is added to make natural rubber strong and more bouncy is – |
| A. | Polythene |
| B. | Sponge |
| C. | Sulphur |
| D. | Chlorine |
| Answer» C. Sulphur | |
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Explanation: Vulcanization is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives" or "accelerators". These additives modify the polymer by forming crosslinks (bridges) between individual polymer chains. Vulcanized materials are less sticky and have superior mechanical properties. |
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| 80. |
White phosphorus is always kept under |
| A. | benzene |
| B. | kerosene |
| C. | ether |
| D. | water |
| Answer» D. water | |
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Explanation: White phosphorus is a material made from a common allotrope of the chemical element phosphorus that is used in smoke, tracer, illumination and incendiary munitions. Other common names include WP, and the slang term "Willie Pete," which is dated from its use in Vietnam, and is still sometimes used in military jargon. As an incendiary weapon, white phosphorus burns fiercely and can set cloth, fuel, ammunition and other combustibles on fire, and cause serious burns or death and that is why it is kept in water. |
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| 81. |
The amount of Chlorine available in water after disinfection is called as – |
| A. | free chlorine |
| B. | residual chlorine |
| C. | free available chlorine |
| D. | combined available chlorine |
| Answer» B. residual chlorine | |
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Explanation: The word "residual" means "remainder" or "that which is left", and as the name suggests the chlorine residual is measure of the amount of chlorine remaining in the water after disinfection. The chlorine residual is usually tested in finished water which is ready to be released into the distribution system, although operators must also ensure that there is adequate residual at the extreme ends of the distribution system. Tests for chlorine residual are probably the most frequently performed tests at water treatment plants. |
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| 82. |
What are the major pollutants of cigarette smoke? |
| A. | Carbon monoxide and dioxin |
| B. | Carbon monoxide and nicotine |
| C. | Carbon monoxide and benzene |
| D. | Dioxin and benzene |
| Answer» B. Carbon monoxide and nicotine | |
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Explanation: Particulate matter consists of millions of tiny particles of diverse chemical composition. Particulate matter from tobacco smoke includes many particles in the size range that reflects light, which explains why tobacco smoke is easily seen by the eye. In contrast to smoke particles, gases emitted by the cigarette such as benzene and carbon monoxide (CO) are invisible to the eye. Particles smaller than 2.5 micrometers (PM2.5) are major components of cigarette smoke and can enter deep into the lung where they can cause serious health problems. |
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| 83. |
The chemical name of 'Common salt' is |
| A. | Sodium chloride |
| B. | Sodium nitrate |
| C. | Ammonium chloride |
| D. | Calcium chloride |
| Answer» A. Sodium chloride | |
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Explanation: Sodium chloride, also known as salt, common salt, table salt or halite, is an ionic compound with the formula NaCl, representing equal proportions of sodium and chloride. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellularfluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative. In solid sodium chloride, each ion is surrounded by six ions of, the opposite charge as expected on electrostatic grounds. |
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| 84. |
By-product obtained by soap industry is – |
| A. | Caustic soda |
| B. | Glycerol |
| C. | Naphthalene |
| D. | Caustic potash |
| Answer» B. Glycerol | |
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Explanation: Glycerol forms the backbone of triglyeerides, and is chiefly produced by saponification of fats as a byproduct of soap- making. It is also a byproduct of the production of biodiesel via transesterification. This form of crude glycerin is often dark in appearance with a thick, syrup-like consistency. |
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| 85. |
Polythene is polymer of – |
| A. | Ethylene |
| B. | Propylene |
| C. | Acetylene |
| D. | Aniline |
| Answer» A. Ethylene | |
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Explanation: The ingredient or monomer is ethylene (IUPAC name ethene). It has the formula C2H4, consisting of a pair of CH2 groups connected by a double bond. Because the catalysts are highly reactive, the ethylene must be of high purity. Typical specifications are <5 ppm for water, oxygen, as well as other alkenes. Acceptable contaminants include N2, ethane (common precursor to ethylene), and methane. Ethylene is usually produced from petrochemical sources, but also is generated by dehydration of ethanol. |
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| 86. |
Who suggested that the most of the mass of atom is located in nucleus? |
| A. | Bohr |
| B. | Thomson |
| C. | Rutherford |
| D. | Avogadro |
| Answer» C. Rutherford | |
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Explanation: The atom, as described by Ernest Rutherford, has a tiny, massive core called the nucleus. The nucleus has a positive charge. |
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| 87. |
Electromagnet is constructed with which of the following? |
| A. | Steel |
| B. | Soft Iron |
| C. | Aluminium |
| D. | Nickel |
| Answer» B. Soft Iron | |
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Explanation: An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. It is made of soft iron since it has the property of losing its magnetism very quickly. |
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| 88. |
Which one of the following is a cation? |
| A. | Carbonate |
| B. | Nitrite |
| C. | Ammonium |
| D. | Hydroxide |
| Answer» C. Ammonium | |
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Explanation: The ammonium cation is a positively charged polyatomic cation with the chemical formula NH4+. |
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| 89. |
Ginger is an example of - |
| A. | Modified Node |
| B. | Modified Root |
| C. | Modified Stem |
| D. | Tap Root |
| Answer» C. Modified Stem | |
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Explanation: Modified stems that grow above ground: Stolons or runners-are horizontally oriented stems that grow along the soil surface. |
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| 90. |
The ore which is found in abundance in India is - |
| A. | monazite |
| B. | bauxite |
| C. | magnetite |
| D. | fluorspar |
| Answer» A. monazite | |
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Explanation: The ore monazite is found in abundance in India. |
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| 91. |
Baryllium Sulphate is less soluble in water due to – |
| A. | High inflammable energy |
| B. | Low Energy of dissociation |
| C. | Low inflammable energy |
| D. | Lonic band |
| Answer» A. High inflammable energy | |
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Explanation: Beryllium sulfate (BeSO4) is a white crystalline e solid. It was first isolated in 1815 by Jons Jakob Berzelelu Beryllium sulfate may be prepared by treatingasne aqueous solution of any beryllium salt with sulfuric acid, followed by evaporation of the solution and crystallization. The hydrated product may be converted to anhydrous salt by heating at 400°C. Beryllium Sulphate is less soluble in water due to High inflammable energy. |
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| 92. |
Which of the following is a not a green house gas? |
| A. | Carbon Dioxide |
| B. | Water Vapour |
| C. | Carbon Monoxide |
| D. | Nitrous Oxide |
| Answer» C. Carbon Monoxide | |
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Explanation: The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone. |
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| 93. |
Heat resistant variety of glass is – |
| A. | Pyrex glass |
| B. | Hard glass |
| C. | Flint glass |
| D. | None of these |
| Answer» C. Flint glass | |
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Explanation: Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion). Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties, which reduces chromatic aberration (colour defects). |
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| 94. |
Among the following iron ores, the highest percentage of iron content is found in— |
| A. | Haemetite |
| B. | Magnetite |
| C. | Limnonite |
| D. | None of these |
| Answer» A. Haemetite | |
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Explanation: Hematite, also spelled haematite, heavy and relatively hard oxide mineral, ferric oxide (Fe2SO3), that constitutes the mostimportant iron ore because of its high iron content (70 percent) and its abundance. Its name is derived from the Greek word for "blood," in allusion to its red colour. Many of the various forms of hematite have separate names. The steel-gray crystals and coarse-grained varieties have a brilliant metallic lustre and are known as specular iron ore; thin scaly types are called micaceous hematite. |
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| 95. |
For determination of the age of which among the following is carbon dating method used? |
| A. | Fossils |
| B. | Rocks |
| C. | Trees |
| D. | 1 & 2 above |
| Answer» D. 1 & 2 above | |
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Explanation: 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. Raw, i.e., uncelebrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" (BP), with "present" defined as CE 1950. Such raw ages can be calibrated to give calendar dates. One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites. |
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| 96. |
The natural source of hydro-carbon is – |
| A. | Crude oil |
| B. | Biomass |
| C. | Coal |
| D. | Carbohydrates |
| Answer» A. Crude oil | |
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Explanation: In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls. Aromatic hydrocarbons (arenes), alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons. The majority of hydrocarbons found naturally occur in crude oil, where decomposed organicmatter provides an abundance of carbon and hydrogen which, when bonded, can catenate to form seemingly limitless chains. |
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| 97. |
Which of the following is chiefly present in LPG (Liquefied Petroleum Gas)? |
| A. | Methane |
| B. | Ethane |
| C. | Propane |
| D. | Butane |
| Answer» D. Butane | |
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Explanation: Liquid petroleum gas is a flammable mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles. It is increasingly used as an aerosol propellant and a refrigerant, replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. it has primarily butane (C4H10). |
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| 98. |
Which one of the following metals is used to galvanise iron? |
| A. | Copper |
| B. | Lead |
| C. | Zinc |
| D. | Mercury |
| Answer» C. Zinc | |
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Explanation: Galvanization) is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. The term is derived from the name of Italian scientist Luigi Galvani. Although galvanization can be done with electrochemical and electro-deposition processes, the most common method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc. |
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| 99. |
Which of the following is not a precious/semi-Precious stone? |
| A. | Sapphire |
| B. | Ruby |
| C. | Pearl |
| D. | Emerald |
| Answer» C. Pearl | |
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Explanation: A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of aclam, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable. |
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| 100. |
What is the name of that system, which uses radioactivity to decide the period of materials of-prehistoric period? |
| A. | Radium dating |
| B. | Uranium dating |
| C. | Carbon dating |
| D. | Deuterium dating |
| Answer» C. Carbon dating | |
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Explanation: 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. |
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