McqMate
| 301. |
Which one of the following organic compound is used to remove stains of iron compounds? |
| A. | Oxalic acid |
| B. | Benzoic acid |
| C. | Phthalic acid |
| D. | Cinnamic acid |
| Answer» A. Oxalic acid | |
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Explanation: Oxalic acid is a reducing agent and its conjugate base, known as oxalate is a chelating agent for metal cations. Oxalic acid's main applications include cleaning or bleaching, especially for the removal of rust, e.g. Bar Keepers Friend is an example of a household cleaner containing oxalic acid. Its utility in rust removal agents is due to its forming a stable, water soluble salt with ferric iron, ferrioxalate ion. |
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| 302. |
Which one of the following pairs is NOT correctly matched? |
| A. | Haematite : Copper |
| B. | Bauxite : Aluminium |
| C. | Monazite : Thorium |
| D. | Pitchblende : Uranium |
| Answer» A. Haematite : Copper | |
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Explanation: Haematite is the mineral form of iron oxide (Fe2O3), one of several iron oxides. It is mined as the main ore of iron. Hematite is harder than pure iron, but much more brittle. |
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| 303. |
Which of the following is used for refrigeration? |
| A. | Sulphur dioxide |
| B. | Chlorine |
| C. | Freon |
| D. | Phosphine |
| Answer» C. Freon | |
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Explanation: Common refrigerants used in domestic refrigerators are Freon, neon and nitrogen. It flows through four components of refrigerator again and again. |
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| 304. |
Electrons in the highest energy level of an atom are called . |
| A. | valence protons |
| B. | orbital protons |
| C. | valence electrons |
| D. | orbital electrons |
| Answer» C. valence electrons | |
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Explanation: The outermost orbital shell of an atom is called its valence shell, and the electrons in the valence shell are valence electrons. |
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| 305. |
Bromine is- |
| A. | Colorless gas insoluble in water |
| B. | A highly inflammable gas |
| C. | A Black solid |
| D. | A red liquid |
| Answer» D. A red liquid | |
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Explanation: Bromine is a chemical element with symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming liquid with a deep red color. At room temperature, Bromine evaporates readily to form a red to amber colored gas. |
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| 306. |
Which is not a type of elements? |
| A. | Metals |
| B. | Non Metals |
| C. | Metalloids |
| D. | Gases |
| Answer» C. Metalloids | |
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Explanation: Element is a chemical substance consisting of atoms having the same number of protons in their atomic nuclei. There are 118 elements that have been identified. The elements classified as metalloids are boron, silicon, germanium, arsenic, antimony, tellurium and polonium. |
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| 307. |
Which among the following is used in making liquors, medicines and as a fuel in aircrafts? |
| A. | Propyl alcohol |
| B. | Dimethyl alcohol |
| C. | Ethyl alcohol |
| D. | Methyl alcohol |
| Answer» C. Ethyl alcohol | |
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Explanation: Ethyl alcohol (C2H5), also known as ethanol, is a member of a class of organic compounds that are given the general name alcohols. |
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| 308. |
The nuclear particles which are assumed to hold the nucleons together are - |
| A. | positrons |
| B. | neutrons |
| C. | electrons |
| D. | mesons |
| Answer» D. mesons | |
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Explanation: The nuclear particles which are assumed to hold the nucleons together are mesons. |
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| 309. |
Milk of magnesia is a suspension of – |
| A. | magnesium sulphate |
| B. | magnesium carbonate |
| C. | magnesium hydroxide |
| D. | magnesium Chloride |
| Answer» C. magnesium hydroxide | |
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Explanation: Milk of magnesia is a suspension of magnesium hydroxide due to its milk-like appearance. |
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| 310. |
Which of the following cannot be beaten into Sheets? |
| A. | Gold |
| B. | Silver |
| C. | Potassium |
| D. | Aluminium |
| Answer» C. Potassium | |
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Explanation: Substances that can be beaten into thin sheets are called malleable. Most metals are malleable. |
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| 311. |
Minamata disease is a nervous disorder caused by eating fish, polluted with |
| A. | Iron |
| B. | Lead |
| C. | Mercury |
| D. | Nickel |
| Answer» C. Mercury | |
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Explanation: Minamata disease is a neurological syndrome caused by severe mercury poisoning Symptoms include ataxia numbness in the hands and feet, general muscle weaknes narrowing of the field of vision and damage to hearing and speech. |
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| 312. |
Which of the following is used to denature ethanol? |
| A. | Methyl alcohol |
| B. | Propyl alcohol |
| C. | Phenol |
| D. | Methane |
| Answer» A. Methyl alcohol | |
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Explanation: Denatured alcohol is ethanol that has additives to make it undrinkable (poisonous), to discourage recreational consumption. Different additives are used to make it difficult. to use distillation or other simple processes to reverse the denaturation. |
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| 313. |
The charcoal used to decolorize brown sugar solution is |
| A. | Wood charcoal |
| B. | Coconut charcoal |
| C. | Animal charcoal |
| D. | Sugar charcoal |
| Answer» C. Animal charcoal | |
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Explanation: A special characteristic of animal charcoal is its power to remove substances from solution. A brown solution of raw sugar is decolourized when boiled with animal charcoal. Other substances that are similarly removed from solution are indigo, litmus, iodine, the colouiing-matter of red wine, the brown matter of peaty water or sewage, astringent principles, and certain basic salts, etc. |
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| 314. |
Which one of the following is used as a sowing agent in the preparation of soft drinks? |
| A. | Phosphoric acid |
| B. | Phosphorus acid |
| C. | Salicylic acid |
| D. | Boric acid |
| Answer» A. Phosphoric acid | |
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Explanation: Phosphoric acid was the foundation of the soft-drink industry, long before Coca-Cola's popularity. Phosphoric acid is deliberately added to soft drinks to give them a sharper flavor. It also slows the growth of molds and bacteria, which would otherwise multiply. |
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| 315. |
The coating of a thin layer of zinc on steel or iron objects is known as – |
| A. | Hot dipping |
| B. | Tinning |
| C. | Galvanising |
| D. | Electroplating |
| Answer» C. Galvanising | |
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Explanation: Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. 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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| 316. |
Which of the following produces highest amount of energy upon oxidation? |
| A. | Protein |
| B. | Fat |
| C. | Glucose |
| D. | An alkane |
| Answer» B. Fat | |
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Explanation: Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure and composition. Although the words "oils", "fats", and "lipids" are all used to refer to fats, "oils" is usually used to refer to fats that are liquids at normal room temperature, while "fats" is usually used to refer to fats that are solids at normal room temperature. |
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| 317. |
Which of the following substance is highly plastic? |
| A. | Quartz |
| B. | Mica |
| C. | Granite |
| D. | Clay |
| Answer» D. Clay | |
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Explanation: Clays exhibit plasticity when mixed with water in certain proportions. When dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur. These reactions, among other changes, cause the clay to be converted into a ceramic material. Because of these properties, clay is used for making pottery items, both utilitarian and decorative. Different types of clay, when used with different minerals and firing conditions, areused to produce earthenware, stoneware, and porcelain. |
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| 318. |
The National Chemical Laboratory (India) is located in – |
| A. | Mumbai |
| B. | Bangaluru |
| C. | Hyderabad |
| D. | Pune |
| Answer» D. Pune | |
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Explanation: NCL, India is a research, development and consulting organization with a focus on chemistry and chemical engineering. It has a successful record of research partnership with industryand is located in pune. NCL belongs to the family of Council of Scientific and Industrial Research (CSIR), the largest chain of public funded research organization in world. NCL's human resources comprise of over 1000 people of whom 350 are scientist, 110 are technical staff with advanced degrees in science, technology or engineering. |
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| 319. |
The major constituent of gobar gas is – |
| A. | Carbon dioxide |
| B. | Methane |
| C. | Butane |
| D. | Isobutane |
| Answer» B. Methane | |
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Explanation: lobar Gas (Methane) is generated by the decomposition of organic cow dung. It consists of 55-65% methane, 30-35% carbon dioxide, with some hydrogen, nitrogen and other traces. The composition of biogas varies depending upon the origin of the anaerobic digestion process. Landfill gas typically has methane concentrations around 50%. |
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| 320. |
The residue left after extracting juice from sugar beet and sugarcane is called – |
| A. | molasses |
| B. | bagasse |
| C. | whey |
| D. | biomass |
| Answer» B. bagasse | |
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Explanation: Bagasse is the fibrous matter that remains after sugarcane or sorghum stalks are crushed to extract their juice. It is currently used as a biofuel and in the manufacture of pulp and paper products and building materials. Agave bagasse is a similar material that consists of the, tissue of the blue agave after extraction of the sap. For each 10 tonnes of sugarcane crushed, a sugar factory produces nearly 3 tonnes of wet bagasse. Since bagasse is a by-product of the cane sugar industry, the quantity of production in each country is in line with the quantity of sugarcane produced. |
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| 321. |
Indane gas is a mixture of which gases? |
| A. | butane and hydrogen |
| B. | butane and propane |
| C. | butane and oxygen |
| D. | methane and oxygen |
| Answer» B. butane and propane | |
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Explanation: 0 |
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| 322. |
Who among the following discovered electron? |
| A. | J.J Thomson |
| B. | Max Born |
| C. | Antoine Lavoisier |
| D. | Mendeleef |
| Answer» A. J.J Thomson | |
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Explanation: Electron was discovered by J. J. Thomson in 1897 when he was studying the properties of cathode ray. |
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| 323. |
Nuclear fission is caused by the impact of - |
| A. | Proton |
| B. | Electron |
| C. | Neutron |
| D. | None of these |
| Answer» C. Neutron | |
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Explanation: Nuclear fission in fissile fuels are the result of the nuclear excitation energy produced when a fissile nucleus captures a neutron. |
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| 324. |
Acid rain is due to air pollution by - |
| A. | Carbon dioxide |
| B. | Carbon monoxide |
| C. | Methane |
| D. | Nitrous oxide and Sulfur dioxide |
| Answer» D. Nitrous oxide and Sulfur dioxide | |
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Explanation: The main chemicals in air pollution that create acid rain are sulfur dioxide (SO2) and Nitrous oxide (N2O). |
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| 325. |
Milk is a natural – |
| A. | Solution |
| B. | Emulsion |
| C. | Mixture |
| D. | Suspension |
| Answer» B. Emulsion | |
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Explanation: An emulsion is a mixture of two or more liquids that are normally immiscible (nonmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both the dispersed and the continuous phase are liquids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). |
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| 326. |
A polymeric substance used to make parachute is – |
| A. | Rayon |
| B. | Viscose |
| C. | Cotton |
| D. | Terylene |
| Answer» B. Viscose | |
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Explanation: Viscose is a viscous organic liquid used to make rayon and cellophane. Viscose is also used as shorthand for Viscose Rayon, thus becoming synonymous with rayon, a soft man-made fibre commonly used in dresses, linings shirts, shorts, coats, jackets, and other outer wear. |
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| 327. |
The metallic Constituents of hard water are – |
| A. | Magnesium, calcium and tin |
| B. | Iron, tin and calcium |
| C. | Calcium, magnesium and iron |
| D. | Magnesium, tin and iron |
| Answer» C. Calcium, magnesium and iron | |
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Explanation: Hard water is water that has high mineral content. In domestic settings, hard water is often indicated by a lack of suds formation when soap is agitated in water. Wherever water hardness is a concern, water softening is commonly used to reduce hard water's adverse effects. |
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| 328. |
The pH of human blood is between – |
| A. | 6.5-7 |
| B. | 7.5-8 |
| C. | 8-9 |
| D. | 4.5-5 |
| Answer» B. 7.5-8 | |
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Explanation: Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. Blood pH is regulated to stay within the narrow range of 7.5 to 8. Blood that has a pH below 7.5 is too acidic, whereas blood pH above 7.5 is too alkaline. |
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| 329. |
Which of the following is used as a lubricant in heavy machines? |
| A. | Bauxite |
| B. | Sulphur |
| C. | Phosphorus |
| D. | Graphite |
| Answer» D. Graphite | |
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Explanation: Graphite is used as a lubricant in heavy machines. it is made of carbon atoms arranged in sheets of hexagonal units - looks a lot like chicken-wire. Another sheet forms on top of this and so on. There is no proper connection (in ideal graphite) between thesheets, so they are able to slide freely over each other without breaking any bonds. |
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| 330. |
What is the element that is in the highest percentage in the composition of the earth? |
| A. | Silicon |
| B. | Oxygen |
| C. | Magnesium |
| D. | Iron |
| Answer» B. Oxygen | |
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Explanation: Earth, our home, is the third planet from the sun. It is the only planet known to have an atmosphere containing free oxygen, oceans of liquid water on its surface, and, of course, life. Earth is the fifth largest of the planets in the solar system smaller than the four gas giants, Jupiter, Saturn, Uranus and Neptune, but larger than the three other rocky planets, Mercury, Mars and Venus. Roughly 71 percent of Earth's surface is covered by water, most of it in the oceans. About a fifth of its atmosphere is made up of oxygen, produced by plants. |
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| 331. |
Formation of ozone hole is maximum over – |
| A. | Africa |
| B. | India |
| C. | Antarctica |
| D. | Europe |
| Answer» C. Antarctica | |
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Explanation: A continent sized hole (thinning) has been formed over Antarctica as a result of damage to ozone. Most ozone is formed in the stratosphere over the equation and spread by winds around the globe. Icy particles in polar stratospheric clouds catalyze the release of chlorine (from CFC) which destroys ozone. The thinning of ozone is maximum because winter there is exceptionally cold. |
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| 332. |
Which of the following is used to iodise common salt? |
| A. | Potassium iodide |
| B. | Iodine |
| C. | Potassium iodate |
| D. | Sodium iodide |
| Answer» C. Potassium iodate | |
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Explanation: Iodized salt (also spelled iodised salt) is table salt mixed with a minute amount of various salts of the element iodine. Table salt with iodide salt slowly loses its iodine content through the process of oxidation and iodine evaporation. Edible salt can be iodised by spraying it with a potassium iodate solution. 60 ml of potassium iodate. |
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| 333. |
Which of the following imparts deep blue colour to glass? |
| A. | Cobalt oxide |
| B. | Cupric oxide |
| C. | Ferrous oxide |
| D. | Nickel oxide |
| Answer» D. Nickel oxide | |
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Explanation: Glass colouring and colour marking may be obtained by addition of colouring ions, by precipitation of nanometer sized colloides (so-called striking glasses such as "ruby gold" or red "selenium ruby"), by coloured inclusions (as in milk glass and smoked glass). |
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| 334. |
Which of the following fibres catches fire least? |
| A. | Nylon |
| B. | Cotton |
| C. | Rayon |
| D. | Terricot |
| Answer» B. Cotton | |
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Explanation: The fibre least prone to catch fire is cotton. Fabrics with more of the fiber surface area exposed to air have more oxygen availableto support, burning and therefore burn more easily. Thus, thin, gauzy fabrics, lace, or brushed fabrics can be very flammable. |
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| 335. |
Drinking soda is – |
| A. | Alkaline |
| B. | Acidic |
| C. | Neutral |
| D. | Oxidant |
| Answer» B. Acidic | |
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Explanation: A soft drink, coke, soda pop, fizzy drink, tonic, .seltzer, mineral, sparkling water or carbonated beverage) is a beverage that typically contains water (often, but not always carbonated water), usually a sweetener, and usually a flavoring agent. The sweetener may be sugar, high-fructose corn syrup, fruit juice, sugar substitutes (in the case of diet drinks) or a combination of these. Soft drinks may also contain caffeine, colourings, preservatives and other ingredients. Soft drinks are called "soft" in contrast to "hard drinks" (alcoholic beverages). |
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| 336. |
The cathode of a lead storage battery is made up of – |
| A. | Zinc |
| B. | Lead |
| C. | Lead oxide |
| D. | Manganese dioxide |
| Answer» B. Lead | |
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Explanation: Lead-acid batteries, invented in 1859 by French physicist Gaston Plante, are the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors. |
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| 337. |
Who is regarded as father of modern chemistry? |
| A. | Ruterford |
| B. | Einstein |
| C. | Lavoisier |
| D. | C.V. Raman |
| Answer» C. Lavoisier | |
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Explanation: Antoine Lavoisier is considered the father of modern chemistry. He was a French nobleman who recognized and named oxygen and isolated the major components of air. |
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| 338. |
Kidney stones are mainly formed by which of the following compound - |
| A. | Sodium chloride |
| B. | Silicates |
| C. | Calcium bicarbonate |
| D. | Calcium oxalate |
| Answer» D. Calcium oxalate | |
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Explanation: Kidney stones form when your urine contains more crystal-forming substances — such as calcium, oxalate and uric acid — than the fluid in your urine can dilute. |
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| 339. |
What is the principal ore of aluminium? |
| A. | Dolomite |
| B. | Copper |
| C. | Lignite |
| D. | Bauxite |
| Answer» D. Bauxite | |
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Explanation: Bacodte is an aluminium ore and is the main source of aluminium. This form of rock consists mostly of the minerals gibbsite, boehmite , and diaspore , in a mixture with the two iron oxides goethite and hematite, the clay mineral kaolinite, and small amounts of anatase TiO2. Bauxite was named after the village Les Baux in southern France, where it was first recognised as containing aluminium and named by the French geologist Pierre Berthier in 1821. |
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| 340. |
Which gas is used as fire extinguisher? |
| A. | Carbon dioxide |
| B. | Carbon monoxide |
| C. | Carbon suboxide |
| D. | Sulphur dioxide |
| Answer» A. Carbon dioxide | |
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Explanation: A fire extinguisher, flame extinguisher, or simply an extinguisher, is anactive fire protection device used to extinguish or control small fires, often in emergency situations. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent which can be discharged. to extinguish a fire. Cartridge-operated extinguishers contain the expellant gas (usually carbon dioxide) in a separate cartridge that is punctured prior to discharge, exposing the propellant to the extinguishing agent. |
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| 341. |
The isotope of Uranium used in atomic reactors is – |
| A. | U^235 (2) |
| B. | U^236 |
| C. | U^237 |
| D. | U^232 |
| Answer» A. U^235 (2) | |
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Explanation: A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines that power either ship's propellers or generators. Some produce isotopes for medical and industrial use, and some are run only for research. When a large fissile atomic nucleus such as U235 or U239 absorbs a neutron, it may undergo nuclear fission. |
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| 342. |
Which one of the following is not a radioactive element? |
| A. | Uranium |
| B. | Thorium |
| C. | Radium |
| D. | Cadmium |
| Answer» D. Cadmium | |
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Explanation: Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation. The most common types of radiation are called alpha, beta, and gamma radiation, but there are several other varieties of radioactivedecay. Among uranium, thorium, radium and cadmium the first three does show radioactive properties while the fourth one does not show any kind of radioactive properties. |
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| 343. |
The anode in a dry cell consists of – |
| A. | Copper |
| B. | Zinc |
| C. | Cadmium |
| D. | Graphite |
| Answer» B. Zinc | |
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Explanation: A "dry-cell" battery is essentially comprised of a metal electrode or graphite rod (elemental carbon) surrounded by a moist electrolyte paste enclosed in a metal cylinder. The cathode is composed of a form of elemental carbon called graphite, which serves as a solid support for the reduction halfreaction. A thin zinc cylinder serves as the anode and it undergoes oxidation. |
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| 344. |
Aspirin is common name of – |
| A. | Salicylic Acid |
| B. | Salicylate |
| C. | Methyl Salicylate |
| D. | Acetyl Salicylic Acid |
| Answer» D. Acetyl Salicylic Acid | |
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Explanation: Aspirin (USAN), also known as acetylsalicylic acid, is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. Aspirin was first isolated by Felix Hoffmann, a chemist with the German company Bayer in 1897. Aspirin also has an antiplatelet effect by inhibiting the production of thromboxane, which under normal circumstances binds platelet molecules together to create a patch over damaged walls of blood vessels. |
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| 345. |
Carbon monoxide is an inflammable gas. Which one of the following is also inflammable? |
| A. | Helium |
| B. | Nitrogen |
| C. | Oxygen |
| D. | Hydrogen |
| Answer» D. Hydrogen | |
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Explanation: At standard temperature and pressure, hydrogen is a colourless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic has with the molecular formula H2. Naturally occurring atomic hydrogen is rare on Earth because hydrogen readily forms covalent compounds with most elements and is present in the water molecule and in most organic compounds. Hydrogen plays a particularly important role in acid-base chemistry with many reactions exchanging protons between soluble molecules. |
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| 346. |
The constituents of automobile exhaust that can cause cancer is/are : |
| A. | Oxides of nitrogen |
| B. | Carbon monoxide |
| C. | Polycyclic hydrocarbons |
| D. | Lead |
| Answer» B. Carbon monoxide | |
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Explanation: Lead is a naturally occuriing bluish-gray metal found in small amounts in the earth's crust. In the past, when lead was added to gasoline, breathing automobile exhaust was the major source of lead exposure for most people. Lead in the exhaust also contaminated the soil near roads. Another major source a exposure is old paint that contains lead. Lead has been found to be carcinogen. A substance that causes cancer or helps cancer grow is called a carcinogen. |
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| 347. |
Hard steel contains – |
| A. | 2 to 5 per cent carbon |
| B. | 0.5 to 1.5 per cent carbon |
| C. | 0.1 to 0.4 per cent carbon |
| D. | 0.01 to 0.04 per cent carbon |
| Answer» B. 0.5 to 1.5 per cent carbon | |
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Explanation: The term hardened steel is often used for a medium or high carbon steel that has been given the heat treatments of quenching followed by tempering. The quenching results in the formation of metastable martensite, the fraction of which is reduced to the desired amount during tempering. This is the most common state for finished articles such as toolsand machine parts,. In contrast, the same steel composition in annealed state will be softer as required for forming and machining. |
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| 348. |
The metals commonly used for electroplating are – |
| A. | Gold, Sodium and Chromium |
| B. | Chromium, Copper and Nickel |
| C. | Nickel, Lead and Chromium |
| D. | Gold, Sodium and Potassium |
| Answer» B. Chromium, Copper and Nickel | |
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Explanation: The process of electroplating takes place as metals in ionic form move from a positive to negative electrode. An electric current passing through the solution causes objects at the cathode or work piece to be coated by the metal in the solution. Electroplating is done for many reasons, usually to beautify, insulate or to protect and to increase the corrosion resistance, conductivity solder ability of metal objects. Plating protects by one of two ways, either sacrificially or mechanically. |
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| 349. |
Which of the following in auto-mobile exhaust can cause cancer? |
| A. | Oxides of nitrogen |
| B. | Carbon monoxide |
| C. | Lead |
| D. | Polyclinic hydrocarbons |
| Answer» B. Carbon monoxide | |
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Explanation: Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion. Domestic wood burning and road traffic are the major sources of PAHs. Exposure to PAH-containing substances increases the risk of cancer in humans. The carcinogenicity of PAHs is associated with the complexity of the molecule, i.e., increasing number of benzenoid 'rings, and with metabolic activation to reactive diol epoxide intermediates and their subsequent covalent binding to critical targets in DNA. |
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| 350. |
Which one of the following gases has the highest calorific value? |
| A. | Natural gas |
| B. | Water gas |
| C. | Coal gas |
| D. | Indane gas |
| Answer» D. Indane gas | |
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Explanation: The basic calorific value for solid and liquid fuels is the gross calorific value at constant volume and for gaseous fuels it is the gross calorific value at constant pressure. The calorific value in Kcal/Kg: Coal: 4000-700Q; Natural gas: 8600; Coal gas: 4000; Water gas: 4600-4800; and LPG (liquefied petroleum gas such as Indane): 11,900 Kcal/Kg. |
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| 351. |
Which type of radiations are absorbed by the upper layer of the atmosphere? |
| A. | Radio-waves |
| B. | Infrared |
| C. | Visible |
| D. | Ultraviolet |
| Answer» D. Ultraviolet | |
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Explanation: The Troposphere is the layer where the weather happens. Above this layer is the Stratosphere and in between them is the Ozone layer that absorbs the sun's harmful ultraviolet rays. Above the Stratosphere is the Mesosphere, the Thermosphere including the Ionosphere - and the Exosphere. |
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| 352. |
The gas which is mainly responsible for the green house effect is: |
| A. | Ozone |
| B. | Oxygen |
| C. | Carbon dioxide |
| D. | Carbon monoxide |
| Answer» C. 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 arewater vapour, carbon dioxide, methane, nitrous oxide, and ozone. |
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| 353. |
Which one of the following is used for dating very old objects of archaeological importance? |
| A. | Phosphorus-31 |
| B. | Tritium |
| C. | Radium |
| D. | Carbon-14 |
| Answer» D. Carbon-14 | |
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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 (140 to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years. After plants die or they are consumed by other organisms (for example, by humans or other animals), the incorporation of all carbon isotopes, including 14C, stops. Thereafter, the concentration (fraction) of 14C declines at a fixed exponential rate due to the radioactive decay of14C. |
|
| 354. |
Which one out of the following helps in burning? |
| A. | carbon dioxide |
| B. | oxygen |
| C. | carbon monoxide |
| D. | nitrogen |
| Answer» B. oxygen | |
|
Explanation: Oxygen is the gas that helps / supports combustion (burning). Nitrogen itself does not support burning (though it forms nitrides with some metals). So, air also supports burning. |
|
| 355. |
Name the gas which is used in balloons in the place of hydrogen? |
| A. | nitrogen |
| B. | helium |
| C. | neorn |
| D. | argon |
| Answer» B. helium | |
|
Explanation: Helium is used in balloons in the place of hydrogen. This is because hydrogen is acombustible gas and when burst can cause skin burns. |
|
| 356. |
The temperature at which both the Fahrenheit and Centigrade scales have the same value is – |
| A. | -60° |
| B. | -40° |
| C. | -20° |
| D. | 0° |
| Answer» B. -40° | |
|
Explanation: The temperature when both the Celsius and Fahrenheit scales are the same is -40 degrees. |
|
| 357. |
The natural resource, known as black gold is – |
| A. | coal |
| B. | lead |
| C. | tin |
| D. | platinum |
| Answer» A. coal | |
|
Explanation: 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. |
|
| 358. |
This group of alumino-silicate minerals is widely used in making electrical insulators |
| A. | Bauxite |
| B. | Chrornite |
| C. | Manganese |
| D. | Mica |
| Answer» D. Mica | |
|
Explanation: 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. |
|
| 359. |
Which of the following is a renewable source of energy? |
| A. | Coal |
| B. | Geothermal powder |
| C. | Natural gas |
| D. | Uranium |
| Answer» B. Geothermal powder | |
|
Explanation: 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. |
|
| 360. |
The rate of change of linear momentum of a body falling freely under gravity is equal to it's |
| A. | Kinetic Energy |
| B. | Weight |
| C. | Potential Energy |
| D. | Impulse |
| Answer» B. Weight | |
|
Explanation: Rate of change of impulse equals the force. In case of freely falling body the only force is the weight. |
|
| 361. |
Isobar is produced by the emission of which of the following? |
| A. | X-ray |
| B. | Gamma ray |
| C. | Beta ray |
| D. | Alpha ray |
| Answer» C. Beta ray | |
|
Explanation: Isobar, in nuclear physics, any member of a group of atomic or nuclear species all of which have the same mass number-that is, the same total number of protons and neutrons. In beta decay, mother and daughter nuclei are always isobars, because either a neutron is converted to a protonor a proton is converted to a neutron in the process. |
|
| 362. |
The main Constituent of natural gas is |
| A. | Methane |
| B. | Ethane |
| C. | Butane |
| D. | Propane |
| Answer» A. Methane | |
|
Explanation: Natural has is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, with other hydrocarbons, carbon dioxide, nitrogen and hydrogen sulfide. It is found in deep underground natural rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates. Petroleum is also another resource found in proximity to and with natural gas. |
|
| 363. |
Domestic cooking gas consists mostly of |
| A. | methane and ethane |
| B. | liquefied butane and isobutene |
| C. | hydrogen and acetylene |
| D. | ethylene and carbon monoxide |
| Answer» B. liquefied butane and isobutene | |
|
Explanation: Domestic gas is another name for Liquefied Petroleum Gas (LPG). Varieties of LPG bought and sold include mixes that are primarily propane (C3H8), primarily butane (C4H10) and, most commonly, mixes including both propane and butane, depending on the season — in winter more propane, in summer more butane. |
|
| 364. |
An example of replenshible energy source is — |
| A. | Coal |
| B. | Petroleum |
| C. | Lignite |
| D. | Biomass |
| Answer» D. Biomass | |
|
Explanation: Biomass is biological material from living, or recently living organisms, most often referring to plants or plant-derived materials. As a renewable energy source, biomass can either be used directly, or indirectly--once or converted into another type of energyproduct such as biofuel. Biomass can be converted to energy in three ways: thermal conversion, chemical conversion, and biochemical conversion. |
|
| 365. |
Which one of the following minerals is found in pure form? |
| A. | Iron |
| B. | Copper |
| C. | Bauxite |
| D. | Manganese |
| Answer» B. Copper | |
|
Explanation: Copper is one of very few elements that are found in essentially pure form in nature. But the bulk of the copper resource is found in other minerals. |
|
| 366. |
Bleaching powder is used in drinking water as a/an – |
| A. | disinfectant |
| B. | antibiotic |
| C. | antiseptic |
| D. | coagulant |
| Answer» A. disinfectant | |
|
Explanation: Bleach refers to a number of chemicals which remove colour, whiten or disinfect, often via oxidation. Bleaches are used as household chemicals to whiten clothes and remove stains and as disinfectants, primarily in the bathroom and kitchen. Many bleaches have strong bactericidal properties, and are used for disinfecting and sterilizing and thus are used in swimming pool sanitation to control bacteria, viruses and algae and in any institution where sterile conditions are needed. |
|
| 367. |
The iron ore which contains 72% of iron is – |
| A. | Magnetite |
| B. | Limonite |
| C. | Haematite |
| D. | Siderite |
| Answer» A. Magnetite | |
|
Explanation: Iron (Fe) is a metallic element and composes about 5% of the Earth's crust. When pure it is a dark, silvery-gray metal. It is a very reactive element and oxidizes (rusts) very easily. The reds, oranges and yellows seen in some soils and on rocks are probably iron oxides. The inner core of the Earth is believed to be a solid iron- nickel alloy. Iron-nickel meteorites are believed to represent the earliest material formed at the beginning of the universe. |
|
| 368. |
Cement is formed by strongly heating a mixture of – |
| A. | limestone and graphite |
| B. | limestone and clay |
| C. | chalk and graphite |
| D. | clay and graphite |
| Answer» B. limestone and clay | |
|
Explanation: Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 degree C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. |
|
| 369. |
Glass is a – |
| A. | superheated solid |
| B. | supercooled liquid |
| C. | supercooled gas |
| D. | superheated liquid |
| Answer» B. supercooled liquid | |
|
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. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. Generally, the structureof a glass exists in a meta-stable state with respect to its crystalline form. |
|
| 370. |
Which one of the following metals does not react with water to produce Hydrogen ? |
| A. | Potassium |
| B. | Cadmium |
| C. | Sodium |
| D. | Lithium |
| Answer» B. Cadmium | |
|
Explanation: Cadmium is a soft, malleable, ductile, bluish-white divalent metal. It is similar in many respects to zinc but forms complex compounds. Unlike other metals, cadmium is resistant to corrosion and as a result it is used as a protective layer when deposited on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes. Cadmium occurs as a minor component in most zinc ores and therefore is a byproduct of zinc production. |
|
| 371. |
Ozone consists of - |
| A. | Oxygen only |
| B. | Oxygen and Nitrogen |
| C. | Hydrogen and Carbon |
| D. | Oxygen and Carbon |
| Answer» A. Oxygen only | |
|
Explanation: Ozone (O3), or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope (O2), breaking down with a half life of roughly 30 minutes in the lower atmosphere, to normal dioxygen. Ozone is formed from dioxygenby the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth's atmosphere. |
|
| 372. |
The greenhouse effect is caused by the higher level of which gas in the atmosphere? |
| A. | Carbon monoxide |
| B. | Carbon dioxide |
| C. | Nitrous oxide |
| D. | Sulphur dioxide |
| Answer» B. Carbon dioxide | |
|
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. The environmental effects of carbon dioxide are of significant interest. |
|
| 373. |
Which one of the following is extensively used for sterilizing water? |
| A. | Bleaching powder |
| B. | Alum |
| C. | Borax powder |
| D. | Soda powder |
| Answer» A. Bleaching powder | |
|
Explanation: Bleaching powder is extensively used in sterilizing water. Calcium hypochlorite is a chemical compound with formula Ca(OCl)2. It is widely used for water treatment and as a bleaching agent (bleaching powder). This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochicnite (liquid bleach). Calcium hypochlorite is a yellow white solid which has a strong smell of chlorine. It is not highly soluble in water, and is more preferably used in soft to medium-hard water. It has two forms: a dry form and a hydrated form. The hydrated form is safer to handle. |
|
| 374. |
Which one of the following acids is used in battery? |
| A. | Hydrochloric acid |
| B. | Hydrofluoric acid |
| C. | Sulphuric acid |
| D. | Sulphurous acid |
| Answer» C. Sulphuric acid | |
|
Explanation: Battery is a device consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy. Possessing different chemical properties, the sulfuric acid has a wide range of applicationsincluding domestic acidic drain cleaner, electrolyte in lead-acid batteries and various cleaning agents. |
|
| 375. |
Natural rubber is a polymer derived from - |
| A. | ethylene |
| B. | propylene |
| C. | isoprene |
| D. | butadiene |
| Answer» C. isoprene | |
|
Explanation: Natural rubber is an addition polymer that is obtained as a milky white fluid known as latex from a tropical rubber tree. |
|
| 376. |
Which one of the following is radioactive? |
| A. | Cesium |
| B. | Platinum |
| C. | Strontium |
| D. | Thorium |
| Answer» D. Thorium | |
|
Explanation: Thorium is a naturally occurring radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 by the Norwegian mineralogist Morten ThraneEsmark and identified by the Swedish chemist JonsJakob Berzelius and named after Thor, the Norse god of thunder. In nature, virtually all thorium is found as thorium-232,which undergoes alpha decay with a half-life of about 14.05 billion years. Other isotopes of thorium are short-lived intermediates in the decay chains of higher elements, and only found in trace amounts. |
|
| 377. |
When iron rusts, its weight : |
| A. | decreases |
| B. | increases |
| C. | remains the same |
| D. | first increases and then decreases |
| Answer» B. increases | |
|
Explanation: When iron rusts, oxide compounds are formed due the interaction between oxygen in the air or in water an the metal. |
|
| 378. |
Which of the following is used as filler in tyre of rubber? |
| A. | Carbon black |
| B. | Coal |
| C. | Coke |
| D. | Graphite |
| Answer» A. Carbon black | |
|
Explanation: The most common use (70%) of carbon black is as a pigment and reinforcing phase in automobile tires. Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage and increasing tire life. |
|
| 379. |
Which of the following alloy is used in making magnet? |
| A. | Duralumin |
| B. | Stainless steel |
| C. | Elniko |
| D. | Magnalium |
| Answer» C. Elniko | |
|
Explanation: A magnetic alloy is a combination of various metals from the periodic table that contains at least one of the three main magnetic elements: iron (Fe), nickel (Ni), and cobalt (Co). |
|
| 380. |
The enzyme that converts glucose to ethyl alcohol is – |
| A. | invertase |
| B. | Maltase |
| C. | Zymase |
| D. | Diastase |
| Answer» C. Zymase | |
|
Explanation: ‘ The fermentation of sugar into ethanol is one of the earliest biotechnologies employed by humanity. Fermentation of fermentable sugars by suitable yeast produces ethanol (ethyl alcohol). Yeast is a single celled fungus containing a number of enzymes useful during fermentation. Brewers yeast and wine yeast, for example, contain zymase, an enzyme that can convert glucose to ethanol. |
|
| 381. |
Who developed Hydrogen Bomb? |
| A. | Wernher Von Braun |
| B. | J. Robert Oppen Heimer |
| C. | Edward Teller |
| D. | Samuel Cohen |
| Answer» C. Edward Teller | |
|
Explanation: Portions of the development and history of the hydrogen bomb remain classified. But it is public knowledge that its chief architect was Dr. Edward Teller. The first H bomb (or thermonuclear bomb / fusion bomb) detonated was on November 1, 1952 in Enewetak in the Marshallislands. The hydrogen bomb is also called the Teller-Ulam design, after Edward Teller and Stanislaw Ulam who helped in the project too. |
|
| 382. |
The fundamental particles present in the nucleus of an atom are - |
| A. | Electron, proton |
| B. | Proton, neutron |
| C. | Neutron, electron |
| D. | Neutron, positron |
| Answer» B. Proton, neutron | |
|
Explanation: The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest. Marsden, under dip direction of Rutherford. The proton— neutron model of nucleus was proposed by Dmity Ivanenko in 1932. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the orbiting electrons. |
|
| 383. |
Bleaching action of moist sulphur dioxide is because of its – |
| A. | basic property |
| B. | acidic property |
| C. | oxidising property |
| D. | reducing property |
| Answer» C. oxidising property | |
|
Explanation: In moist conditions, sulphur dioxide is a bleaching agent. In the reducing action of SO2, oxygen is removed from coloured dye. Sulphur dioxide is used to bleach wool and silk. Salts of sulphur dioxide are also used in bleaching. Calcium hydrogen sulphite Ca(HSO3)2 is used to whiten wood pulp in the manufacturing of paper. |
|
| 384. |
The long range potential of nuclear energy in India depends on its reserves of – |
| A. | thorium |
| B. | uranium |
| C. | plutonium |
| D. | radium |
| Answer» B. uranium | |
|
Explanation: India's domestic uranium reserves are small and the country is dependent on uranium imports to fuel its nuclear power industry. Since early 1990s, Russia has been a major supplier of nuclear fuel-to India. |
|
| 385. |
Which of the following gases will effuse out of football bladder most wieldy? |
| A. | He |
| B. | H2 |
| C. | N2 |
| D. | 02 |
| Answer» B. H2 | |
|
Explanation: Hydrogen is a chemical element with symbol H and atomic number 1. With an average atomic weight of 1.00794 u (1.007825 u for hydrogen-1), hydrogen is the lightest element and its monatomic form (H1) is the most abundant chemical substance, constituting roughly 75% of the Universe's baryonic mass. Naturally occurring atomic hydrogen is rare on Earth because hydrogen readily forms covalent compounds with most elements and is present in the-water molecule and in most organic compounds. |
|
| 386. |
Silk fibre chemically is – |
| A. | Carbohydrate |
| B. | Fat |
| C. | Protein |
| D. | Cellulose |
| Answer» C. Protein | |
|
Explanation: Silk is a natural protein fibre, some forms of which can be woven into textiles. The protein fibre of silk is composed mainly of fibroin and produced by certain insect larvae to form cocoons. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyxmorireared in captivity (sericulture). The shimmering appearance of silk is due to the triangular prism- like structure of the silk fibre, which allows silk cloth to refract incoming light at different angles, thus producing different colours. |
|
| 387. |
Milk tastes sour when it is left in open for some time. This happens due to the formation of |
| A. | Lactic acid |
| B. | Citric acid |
| C. | Acetic acid |
| D. | Carbonic acid |
| Answer» A. Lactic acid | |
|
Explanation: Milk contains a sugar called lactose, a disaccharide (compound sugar) made by the glycosidic bonding between glucose and glactose (monosaccharides). When milk is heated to a temperature of 30-40 degrees centigrade and a small amount of old curd added to it, the lactobacillus in that curd sample gets activated and multiplies. These convert the lactose into lactic acid, which imparts the sour taste to curd. |
|
| 388. |
The polymerisation of which of the Following is used in manufacturing of polythene in industry? |
| A. | Methane |
| B. | Styrene |
| C. | Acetylene |
| D. | Ethylene |
| Answer» D. Ethylene | |
|
Explanation: Ethylene is a rather stable molecule that polymerizes only upon contact with catalysts. The conversion is highly exothermic, that is the process releases a lot of heat. Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. |
|
| 389. |
Which of the following substances undergoes chemical change on heating? |
| A. | Sodium chloride |
| B. | Silica |
| C. | Lead nitrate |
| D. | Platinum wire |
| Answer» C. Lead nitrate | |
|
Explanation: Lead nitrate on heating decomposes to lead monoxide, nitrogen dioxide and oxygen. NO2 is liberated, along with oxygen, as a reddish brown gas. |
|
| 390. |
Who proposed first atomic theory? |
| A. | E. Rutherford |
| B. | De Broglie |
| C. | John Dalton |
| D. | D. I. Mendeleev |
| Answer» C. John Dalton | |
|
Explanation: Democritus first suggested the existence of the atom but it took almost twomillennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). |
|
| 391. |
Which one of the following has the highest fuel value? |
| A. | Hydrogen |
| B. | Charcoal |
| C. | Natural gas |
| D. | Gasoline |
| Answer» A. Hydrogen | |
|
Explanation: Hydrogen has the highest calorific value of (141,790 KJ/kg ) thus have highest fuel value. Calorific value of charcoal, natural gas and gasoline are (29,600; 43,000; 47,300 kJ/ kg) respectively. |
|
| 392. |
The major constituent of air is – |
| A. | nitrogen |
| B. | carbon dioxide |
| C. | oxygen |
| D. | hydrogen |
| Answer» A. nitrogen | |
|
Explanation: Depending on various geographical locations these may change, but for the most part air is made up of 78% nitrogen (N2), 21% oxygen (O2), and trace amounts of carbon dioxide (CO2), methane (CH4) hydrogen (H2), argon (AO and helium (He). The CO2, CH4, H2, Ar, and He, when combined together, make up about 1% of our air. Nitrogen is a chemical element with symbol N and atomic number 7. Elemental nitrogen is a colourless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.09% by volume of Earth's atmosphere. |
|
| 393. |
Cream gets separated out of milk when it is churned. This is due to– |
| A. | gravitational force |
| B. | centripetal force |
| C. | centrifugal force |
| D. | frictional force |
| Answer» C. centrifugal force | |
|
Explanation: During the churning of buttermilk, many particles of curd undergorotatory motion: Then the particles with less weight experience more centripetal force and hence those particles accumulate at the center. Heavier particles experience more centrifugal force and so they are forced to the walls of the container away from the centre. |
|
| 394. |
Lime water turns milky when carbon dioxide is passed through it. It is due to the for mation of: |
| A. | Calcium Carbonate |
| B. | Barium Carbonate |
| C. | Calcium Hydrogen Carbonate |
| D. | Calcium Oxide |
| Answer» A. Calcium Carbonate | |
|
Explanation: When carbon dioxide is passed through lime water for a short time, it turns lime water milky due to formation of a white precipitate of calcium carbonate. |
|
| 395. |
German silver is an alloy of - |
| A. | copper, nickel and silver |
| B. | silver, copper and aluminium |
| C. | zinc, copper and nickel |
| D. | silver, zinc and copper |
| Answer» C. zinc, copper and nickel | |
|
Explanation: German silver is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. |
|
| 396. |
One of the constituents of tear gas is - |
| A. | Ethane |
| B. | Ethanol |
| C. | Ether |
| D. | Chloropicrin |
| Answer» D. Chloropicrin | |
|
Explanation: Chloropicrin is a colourless liquid that is insoluble in water, with which it is stable. With a vapor pressure of 24 mm Hg, its volatility is between that of phosgene and mustard has in persistency, although closer to phosgene because it is related to the compound. Tests have shown that chloropicrin causes humans to shut their eyes involuntarily.Chloropicrin can be absorbed systemically through inhalation, ingestion, and the skin. |
|
| 397. |
An atomic clock is based on transitions in - |
| A. | Sodium |
| B. | Caesium |
| C. | Magnesium |
| D. | Aluminium |
| Answer» B. Caesium | |
|
Explanation: An atomic clock is a clock device that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the wave frequency of television broadcasts, and in global navigation satellite systems such as GPS. |
|
| 398. |
The temperature of oxyacetylene flame is around – |
| A. | 2800°C |
| B. | 3200°C |
| C. | 4000°C |
| D. | 1500°C |
| Answer» B. 3200°C | |
|
Explanation: Flames are formed when a fuel gas, like acetylene, reacts with a support has such as oxygen. This reaction creates a lot of heat and light, which we see as a flame. An oxygen acetylene flame can create temperatures over 3200°C. Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the work piece material (e.g. steel) in a room environment. |
|
| 399. |
What product is formed when electricity is passed throughan aqueous solution of sodium chloride? |
| A. | Sodium and water |
| B. | Sodium oxide |
| C. | Sodium and chlorine |
| D. | Sodium hydroxide |
| Answer» D. Sodium hydroxide | |
|
Explanation: When electricity is passed through an aqueous solution of sodium chloride, it gives hydrogen, chlorine and sodium hydroxide as a product. |
|
| 400. |
The atmospheric gas that is mainly responsible for Green House effect – |
| A. | Ozone |
| B. | Nitrogen |
| C. | Oxygen |
| D. | Carbondioxide |
| Answer» D. Carbondioxide | |
|
Explanation: A greenhouse was (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. |
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