McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: General Knowledge (GK) .
| 101. |
Cement is made hard with – |
| A. | dehydration |
| B. | hydration and dissociation of water |
| C. | Dissociation of water |
| D. | Polymerisation |
| Answer» B. hydration and dissociation of water | |
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Explanation: Cements (e.g., Portland cement) harden because of hydration, chemical reactions that occur independently of the mixture's water content; they can harden even underwater or when constantly exposed to wet weather. The chemical reaction that results when the anhydrous cement powder is mixed with water produces hydrates that are not water - soluble. |
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| 102. |
Which of the following gas leaked in the Bhopal Gas tragedy in December 1984? |
| A. | Methyl isocyanate |
| B. | Methyl isochlorate |
| C. | Methyl phosphate |
| D. | Methyl isopropate |
| Answer» A. Methyl isocyanate | |
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Explanation: In the gas tragedy that occurred at the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh, on 2-3 December 1984. |
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| 103. |
Which acid is used in rubber, textile, leather and electroplating industries? |
| A. | Ethanoic acid |
| B. | Methanoic acid |
| C. | Malanic acid |
| D. | Butairic acid |
| Answer» B. Methanoic acid | |
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Explanation: 0 |
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| 104. |
Study of Fossils is known as? |
| A. | Paleontology |
| B. | Petrology |
| C. | Seismology |
| D. | None of the above |
| Answer» A. Paleontology | |
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Explanation: Paleontology is the study of the history of life on Earth as based on fossils. Fossils are the remains of plants, animals, fungi, bacteria, and single-celled living things that have been replaced by rock material or impressions of organisms preserved in rock. |
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| 105. |
A substance which readily forms colloidal solution in contact with water is called – |
| A. | Extrinsic colloid |
| B. | Associated colloid |
| C. | Hydrophobic colloid |
| D. | Hydrophilic colloid |
| Answer» D. Hydrophilic colloid | |
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Explanation: A colloidal dispersion in which the dispersed particles are more or less liquid and exert a certain attraction on and absorb a. certain quantity of the fluid in which they are suspended is called as hydrophilic colloid. Molecules of a hydrophilic colloid have an affinity for water molecules and when dispersed in water become hydrated. Hydrated colloids swell and increase the viscosity of the system,thereby improving stability by reducing the interaction between particles and their tendency to settle. They may also possess a net surface electrical charge. |
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| 106. |
Denatured spirit is ethanol mixed with |
| A. | Petrol |
| B. | Kerosene |
| C. | Water |
| D. | Pyridine |
| Answer» D. Pyridine | |
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Explanation: Denatured alcohol or methylated spirits is ethanol that has additives to make it undrinkable (poisonous), to discourage recreational consumption. In some cases it is also dyed. Denatured alcohol is used as a solvent and as fuel for spirit burners and camping stoves. Because of the diversity of industrial uses for denatured alcohol, hundreds of additives and denaturing methods have been used. |
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| 107. |
The most abundant inert gas in the atmosphere is – |
| A. | Helium |
| B. | Neon |
| C. | Argon |
| D. | Krypton |
| Answer» C. Argon | |
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Explanation: Argon is the third most common gas in the Earth's atmosphere, at 0.93% (9,300 ppm), making it approximately 23.8 times as abundant as new most common atmospheric gas, carbon dioxide (390 ppm), and more than 500 times as abundant as the next most common noble gas, neon (18 ppm). Nearly all of this argon is radiogenic argon-40 derived from the decay. of potassium-40 in the Earth's crust. |
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| 108. |
Nuclear energy is a mineral-based energy source. It is derived from – |
| A. | uranium |
| B. | thorium |
| C. | plutonium |
| D. | All tithe above |
| Answer» A. uranium | |
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Explanation: The sun and stars are seemingly inexhaustible sources of energy. That energy is the result of nuclear reactions, in which matter is converted to energy. We have been able to harness that mechanism and regularly use it to generate power. Presently, nuclear energy provides for approximately 16% of the world's electricity. Unlike the stars, the nuclear reactors that we have today work on the principle of nuclear fission. |
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| 109. |
Zinc sulphide is commonly used as – |
| A. | fungicide |
| B. | herbicide |
| C. | rodenticide |
| D. | deodorant |
| Answer» C. rodenticide | |
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Explanation: Rodenticides are a category of pest control chemicals intended to kill rodents. Metal phosphides have been used as a means of killing rodents and are considered single-dose fast acting rodenticides (death occurs commonly within 1-3 days after single bait ingestion). A bait consisting of food and a phosphide (usually zinc phosphide) is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. |
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| 110. |
Galena is a mineral of – |
| A. | iron |
| B. | gold |
| C. | lead |
| D. | calcium |
| Answer» C. lead | |
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Explanation: Galena is the natural mineral form of lead (II) sulfide. It is the most important lead ore mineral. Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite. Galena deposits often contain significant amounts of silver as included silver sulfide mineral phases or as limited solid solution within the galena structure. |
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| 111. |
Magnalium is an alloy of – |
| A. | Aluminium and Magnesium |
| B. | Magnesium and Tin |
| C. | Aluminium and Zinc |
| D. | Manganese and Magnesium |
| Answer» A. Aluminium and Magnesium | |
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Explanation: MagnaHum is an aluminium alloy with 1.5 to 2% magnesium and small amounts of copper, nickel, and tin. Some alloys, intended for particular uses at the cost of poor corrosion resistance, may consist of up to 50% magnesium. It finds use in engineering and pyrotechnics. Alloys with smaller amounts of magnesium (about 5%) exhibit greater strength, greater corrosion resistance, and lower density than pure aluminium. |
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| 112. |
Which of the toxic heavy metals is found in modern tannery industries? |
| A. | Nickel |
| B. | Zine |
| C. | Chromium |
| D. | Lead |
| Answer» C. Chromium | |
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Explanation: Chromium is mainly found in waste from the chrome tanning process; it occurs as part of the retanning system and is displaced from leathers during retanning and dyeing processes. This chrome is discharged from processes in soluble form; however, when mixed with tannery waste waters from other processes (especially if proteins are present), the reaction is very rapid. Precipitates are formed, mainly proteinchrome, which add to sludge generation. |
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| 113. |
Which of the following contains high content of lead? |
| A. | Coal |
| B. | Cooking gas |
| C. | High octane fuel |
| D. | Low octane fuel |
| Answer» C. High octane fuel | |
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Explanation: A high-octane-rated fuel, such gasoline contains lead. Straight-run gasoline isdistilled directly from crude oil. Once the leading source of fuel, its low octane rating required lead additives. Most countries have phased out leaded fuel. Different additives have replaced the lead compounds. The most popular additives include aromatic hydrocarbons, ethers and alcohol (usually ethanol or methanol). Lead used to be added to petrol and this was the source of high levels of lead in the air. |
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| 114. |
Acids on reacting with metals release which of the following gases? |
| A. | Oxygen |
| B. | Carbon Dioxide |
| C. | Hydrogen |
| D. | Methane |
| Answer» C. Hydrogen | |
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Explanation: Acids on reacting with some reactive metals result in the formation of a salt and hydrogen gas. The general equation that describes the chemical reaction between an acid and metal is Metal + acid = salt + hydrogen gas. |
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| 115. |
Carbon reacts with metal to form - |
| A. | Carbide |
| B. | Carbonate |
| C. | Hydroxide |
| D. | Oxide |
| Answer» A. Carbide | |
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Explanation: Carbon reacts with reactive metals, such as tungsten, carbon forms either carbides to form alloys with high melting points. |
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| 116. |
Radioactive disintegration of Uranium ultimately results in formation of - |
| A. | Radium |
| B. | Thorium |
| C. | Polonium |
| D. | Lead |
| Answer» D. Lead | |
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Explanation: Radioactive decay (also known as nuclear decay, radioactivity or nuclear radiation) is the process by which an unstable atomic nucleus loses energy (in terms of mass in its rest frame) by emitting radiation |
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| 117. |
Energy use in solar cookers, solar distillation plants, solar power plants is known as – |
| A. | chemical energy |
| B. | solar energy |
| C. | thermal energy |
| D. | nuclear energy |
| Answer» B. solar energy | |
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Explanation: Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis. |
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| 118. |
'Vinegar' is a commercial name of – |
| A. | Oxalic acid |
| B. | Hydrochloric acid |
| C. | Acetic acid |
| D. | Citric acid |
| Answer» C. Acetic acid | |
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Explanation: Vinegar is a liquid substance consisting mainly of acetic acid (CH3CO2H) and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. It is today mainly used in the kitchen as a general cooking ingredient. |
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| 119. |
Which metal does not undergo corrosion due to the formation of oxide layer? |
| A. | Copper |
| B. | Iron |
| C. | Aluminium |
| D. | Zinc |
| Answer» C. Aluminium | |
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Explanation: Corrosion is an oxidation reaction with atmospheric oxygen in the presence of water on the surface of a metal. Iron corrodes more quickly than most other transition metals to form an iron oxide. Aluminium also undergoes an oxidation reaction, but does not oxidize and corrode as quickly as its reactivity suggests. Once a thin oxide layer of Al2O3 has formed on the surface, it forms a barrier tooxygen and water to prevent further corrosion of the aluminium. |
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| 120. |
The acid present in red ants is – |
| A. | Acetic acid |
| B. | Butyric acid |
| C. | Caproic acid |
| D. | Formic acid |
| Answer» D. Formic acid | |
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Explanation: Formic acid is the simplest carboxylic acid. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant. Formica, referring to its early isolation by the distillation of ant bodies. |
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| 121. |
The metal extracted from Bauxite is – |
| A. | Silver |
| B. | Copper |
| C. | Manganese |
| D. | Aluminum |
| Answer» D. Aluminum | |
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Explanation: 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 as of 2010. Usually, bauxite ore is heated in a pressure vessel along with a sodium hydroxide solution at a temperature of 150 to 200 °C. At these temperatures, the aluminium is dissolved as an aluminate (the Bayer process). |
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| 122. |
pH value between 6.5-7.5 makes the soil |
| A. | Basic |
| B. | Neutral |
| C. | Acidic |
| D. | None of these |
| Answer» D. None of these | |
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Explanation: In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. P [H], which measures the hydrogen ion concentration is closely related to, and is often written as, pH. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 aresaid to be acidic and solutions with a pH greater than 7 are basic or alkaline. A pH of 7 is treated as neutral. |
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| 123. |
The metal chiefly used for galvanizing iron is: |
| A. | Zine |
| B. | Mercury |
| C. | Cadmium |
| D. | Tin |
| Answer» A. Zine | |
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Explanation: Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. In current use, the term refers to the coating of steel or iron with zinc. This is done to prevent rusting of the ferrous item. The value of galvanizing stems from the corrosion resistance of zinc, which, under most service conditions, is considerably greater than that of iron and steel. |
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| 124. |
Submarines move under water. They have engines that run on - |
| A. | Petrol and oxygen |
| B. | Diesel |
| C. | Batteries |
| D. | Steam |
| Answer» B. Diesel | |
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Explanation: Early submarines used a direct mechanical connection between the engine and propeller, switching between diesel engines for surface running, and electric motors for submerged propulsion. Dieselelectric submarines have a stealth advantage over their nuclear Counterparts. |
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| 125. |
The Bhopal gas tragedy was caused by the gas - |
| A. | Methyl chloride |
| B. | Methyl Iso Cyanide |
| C. | Methyl Iso Cyanate |
| D. | Methyl Cyanide |
| Answer» C. Methyl Iso Cyanate | |
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Explanation: The Bhopal disaster occurred on the night of 2-3 December 1984 at the Union Carbide India Limited (UCIL) pesticide plant inBhopal, Madhya Pradesh. Over 500,000 people were exposed to methyl isocyanate has and other chemicals. The toxic substance made its way in and around the shantytowns located near the plant. |
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| 126. |
The wine is prepared by the process of |
| A. | fermentation |
| B. | catalysation |
| C. | conjugation |
| D. | displacement |
| Answer» A. fermentation | |
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Explanation: After the destemmer the wine is pumped into tanks to begin fermentation. The process of fermentation in winemaking turns grape juice into an alcoholic beverage. |
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| 127. |
Fission and fusion are called - |
| A. | molecular reactions |
| B. | potential reactions |
| C. | nuclear reactions |
| D. | heat reactions |
| Answer» C. nuclear reactions | |
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Explanation: The energy harnessed in nuclei is released in nuclear reactions. Fission is the splitting of a heavy nucleus into lighter nuclei and fusion is the combining of nuclei to form a bigger and heavier nucleus. Fission and fusion are called nuclear reactions |
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| 128. |
Acids on reacting with metal carbonates release which of the following gases? |
| A. | Hydrogen sulphide |
| B. | Carbon Dioxide |
| C. | Propane |
| D. | Hydrogen |
| Answer» B. Carbon Dioxide | |
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Explanation: When an acid reacts with a metal carbonate, a salt, water and carbon dioxide are produced: Acid + metal carbonate → salt + water + carbon dioxide |
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| 129. |
Which of the following is released during photosynthesis? |
| A. | Oxygen |
| B. | Carbon dioxide |
| C. | Energy |
| D. | Light |
| Answer» A. Oxygen | |
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Explanation: Plants use photosynthesis as a way of producing glucose. They take in light energy from the sun and water and carbon dioxide from the air. This is then used to produce oxygen and glucose. 6CO2 + 6 H2O → C6H12O6 + 6O2 |
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| 130. |
Who discovered electron? |
| A. | E. Goldstien |
| B. | J. J. Thomson |
| C. | Ernest Rutherford |
| D. | J. Chadwick |
| Answer» B. J. J. Thomson | |
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Explanation: J.J. Thomson is credited with the discovery and identification of the electron. Thomson, in 1897, was the first to suggest that one of the fundamental units was more than 1,000 times smaller than an atom, suggesting the sub atomic particle now known as the electron. |
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| 131. |
Which of the following is also known as Carbolic Acid? |
| A. | Phenol |
| B. | Hydroxide |
| C. | Sulphuric Acid |
| D. | Ethanol |
| Answer» A. Phenol | |
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Explanation: Phenol is also known ascarbolic acid. It is an aromatic organic. |
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| 132. |
Galvanization of iron is carried out using – |
| A. | Zinc |
| B. | Tin |
| C. | Copper |
| D. | Chromium |
| Answer» A. 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 electrodeposition 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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| 133. |
Cokking gas is a mixture of - |
| A. | methane and ethylene |
| B. | carbon dioxide and oxygen |
| C. | butane and propane |
| D. | carbon monoxide and carbon dioxide |
| Answer» C. butane and propane | |
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Explanation: Liquefied petroleum gas, also called LPG, GPL, LP Gas, liquid petroleum gas or simply propane or butane, 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. When specifically used as a vehicle fuel it is often referred to as autogas. |
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| 134. |
The purest form of water is – |
| A. | tap water |
| B. | rain water |
| C. | ground water |
| D. | distilled water |
| Answer» B. rain water | |
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Explanation: Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated—that is, become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystem, as well as water for hydroelectric power plants and crop irrigation. The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. |
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| 135. |
The main constituent of biogas is – |
| A. | oxygen |
| B. | methane |
| C. | acetic acid |
| D. | methyl alcohol |
| Answer» B. methane | |
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Explanation: Biogas typically refers to a gas produced by breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal feces, and kitchen waste can be converted into a gaseous fuel called biogas. Biogas originates from biogenic material and is a type of bio fuel. Biogas is produced by the anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material, and crops. |
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| 136. |
Which metal is extracted from sea water? |
| A. | Potassium |
| B. | Magnesium |
| C. | Aluminium |
| D. | Beryllium |
| Answer» B. Magnesium | |
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Explanation: The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine. Commercially, the chief use for the metal is as an alloying agent to make aluminium- magnesium alloys, sometimes called "magnalium" or "magnelium". Since magnesium is less dense than aluminium, these alloys are prized for their relative lightness and strength. Magnesium is the fourth most common element in the Earth as a whole (behind iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. |
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| 137. |
Percentage of lead in lead pencils is – |
| A. | "0" |
| B. | 31-66 |
| C. | 40 |
| D. | 80 |
| Answer» A. "0" | |
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Explanation: There is no lead in pencils. Rather, the core is made up of non-toxic mineral called graphite. The common name "pencil lead" is due to an historic association with the stylus made of lead in ancient Roman times. Most pencil cores are made of graphite mixed with a clay binder, leaving grey or black marks that can be easily erased. Graphite pencils are used for both writing and drawing, and the result is durable: although writing can usually be removed with an eraser, it is resistant to moisture, most chemicals, ultraviolet radiation and natural aging. |
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| 138. |
When formaldehyde and potassium hydroxide are heated, we get – |
| A. | Acetylene |
| B. | Methyl alcohol |
| C. | Methane |
| D. | Ethyl formate |
| Answer» B. Methyl alcohol | |
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Explanation: When formaldehyde and potassium hydroxide are heated,we get methyl alcohol and formic acid. it is cannizarroo reaction. The Cannizzaro reaction, named after its discoverer StanislaoCannizzaro, is a chemical reaction that involves the base-induced disproportionation of an aldehyde. Cannizzaro first accomplished this transformation in 1853, when he obtained benzyl alcohol and potassium benzoate from the treatment of benzaldehyde with potash (potassium carbonate). |
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| 139. |
When conc. H2SO4 is added to diy KNO3, brown fumes are evolved. These fumes are due to – |
| A. | SO3 |
| B. | SO2 |
| C. | NO2 |
| D. | N2O |
| Answer» C. NO2 | |
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Explanation: when concentrated hydrosulphuric acid is added to dry potassium nitrate brown fumes are evolved and these fumes are evolved due to the formation of nitrogen dioxide. Nitrogen dioxide is the chemical compound with the formula NO2. It is one of several nitrogen oxides. NO2 is an intermediatein the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odour and is a prominent air pollutant. Nitrogen dioxide is a paramagnetic and bent molecule. |
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| 140. |
Pasteurisation of milk means – |
| A. | heating of milk to above 72°C |
| B. | heating of milk to above 62°C |
| C. | cooling of milk to about 62°C |
| D. | cooling of milk to about 10°C |
| Answer» B. heating of milk to above 62°C | |
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Explanation: Pasteurization typically uses temperatures below boiling, since at very high temperatures, casein micelles will irreversibly aggregate, or "Curdle". The two main types of pastemization used today are: high-temperature, short-time (HTST) and "extended shelf life" (ESL) treatment. Ultra-high temperature (UHT or ultra-heat-treated) is also used for milk treatment. |
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| 141. |
Aluminium can be purified by – |
| A. | oxidation |
| B. | distillation |
| C. | electrolysis |
| D. | ozonolysis |
| Answer» C. electrolysis | |
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Explanation: Electrolysis is a method of using a direct electric current (DC) to drive an otherwise non-spontaneous chemicaireaction. Electrolysis is commercially highly important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. Aluminum is extracted from its oxide ore "Bauxite". |
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| 142. |
Which among the following elements is found in maximum percentage in the human body? |
| A. | Carbon |
| B. | Hydrogen |
| C. | Nitrozen |
| D. | Oxyzen |
| Answer» D. Oxyzen | |
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Explanation: Most of the human body is made up of water, H2O, with cells consisting of 65- 90% water by weight. Therefore, it isn't surprising that most of a human body's mass is oxygen. Carbon, the basic unit for organic molecules, comes in second. 99% of the mass of the human body is made up of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. |
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| 143. |
Which of the following acids is present in sour milk? |
| A. | Formic acid |
| B. | Lactic acid |
| C. | Citric acid |
| D. | Tartaric acid |
| Answer» B. Lactic acid | |
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Explanation: Sour Tasting milk products, like yogurt, butter milk, etc developed sour taste as milk is cultured with lactic acid bacteria. |
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| 144. |
Non-metallic oxides are in nature. |
| A. | Basic |
| B. | Acidic |
| C. | Neutral |
| D. | None of the above |
| Answer» B. Acidic | |
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Explanation: Reaction between a non-metallic oxide and an acid leads to the formation of a salt and water. This is similar to the reaction between a base and an acid; we can conclude that nonmetallic oxides are acidic in nature. |
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| 145. |
Detergents used for cleaning clothes and utensils contain – |
| A. | nitrates |
| B. | bicarbonates |
| C. | sulphonates |
| D. | bismuthates |
| Answer» C. sulphonates | |
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Explanation: Sulphonate is a detergent used for cleaning clothes and utensils. It is a salt or ester of any sulphonic acid. |
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| 146. |
Radioactive disintegration of uranium ultimately results in formation of – |
| A. | radium |
| B. | thorium |
| C. | polonium |
| D. | lead |
| Answer» D. lead | |
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Explanation: Uranium-lead (U-Pb) dating is one of the oldest and most refined of the radiometric dating schemes, with a routine age range of about 1 million years to over 4.5 billion years, and with routine precisions in the 0.1-1 percent range. |
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| 147. |
Impure camphor is purified by – |
| A. | sublimation |
| B. | fractional crystallisation |
| C. | fractional distillation |
| D. | steam distillation |
| Answer» A. sublimation | |
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Explanation: Sublimation apparatus is a piece of laboratory glassware used in the technique of sublimation usually used by chemists to purify compounds. Typically a solid is placed in a vessel which is then heated under vacuum. Under this reduced pressure the solid volatilizes and condenses as a purified compound on a cooled surface, leaving the non-volatile residue impurities behind. This cooled surface often takes the form of a cold finger. Once heating ceases and the vacuum is released, the sublimed compound can be collected from the cooled surface. Impure camphor is purified by this process. |
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| 148. |
Which among the following stage is suitable indicator when solution of sodium carbonate is mixed with sulphuric acid? |
| A. | Methylene blue |
| B. | Methyl red |
| C. | Phenolphthaline |
| D. | Methyl orange |
| Answer» D. Methyl orange | |
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Explanation: Methyl orange is a pH indicator frequently used in titrations. It is often used in titrations because of its clear and distinct colour change. Because it changes colour at the pH of a mid-strength acid, it is usually used in titrations for acids. |
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| 149. |
In which of the following states maximum iron are is found? |
| A. | FeCO3 |
| B. | Fe2O3 |
| C. | Fe3O4 |
| D. | FeS2 |
| Answer» B. Fe2O3 | |
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Explanation: Iron ores are rocks and minerals from which metallic iron can be economically extracted. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH), limonite (FeO(OH).n(H2O)) or siderite (FeCO3). Hematite, also spelled as haematite, is the mineral form of iron(III) oxide (Fe2O3), one of several iron oxides. It is mined as the main ore of iron. Huge deposits of hematite are found in banded iron formations. Gray hematite is typically found in places where there has been standing water or mineral hot springs, such as those in Yellowstone National Park in the United States. |
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| 150. |
Greenhouse effect is caused by – |
| A. | nitrogen |
| B. | carbon dioxide |
| C. | carbon monoxide |
| D. | nitrogen dioxide |
| Answer» B. carbon dioxide | |
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Explanation: The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. By their percentage contribution to the d effect on Earth the four major gases are: water vapor, 36-70%, carbon dioxide, 9- 26%, methane, 4-9% and ozone, 3-7%. |
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