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Chemistry |
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| 1)Pure water can be obtained from sea water by the process of | |||
| filtration | distillation | ||
| evaporation | fractional distillation | ||
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| 2)Common salt can be obtained from sea water by the process of | |||
| sublimation | filtration | ||
| evaporation | crystallisation | ||
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| 3)Gasoline can be obtained from crude oil by the process of | |||
| evaporation | crystallisation | ||
| distillation | fractional distillation | ||
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| 4)An electric kettle used for boiling hard water has a white scale diposited on its heation element. This consists of | |||
| common salt | sugar | ||
| sodium carbonate | carbonates of calcium and magnesium | ||
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| 5)Washing soda is | |||
| hydrated sodium carbonate | sodium chloride | ||
| sodium bicarbonate | calcium carbonate | ||
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| 6)Hard water does not lather well with soap because | |||
| it contains carbonates of calcium and magnesium | it contains suspended impurities | ||
| it contains sodium chloride | none of these | ||
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| 7)Water, on passing over rocks, becomes hard because it disolves | |||
| sodium chloride | sodium carbonate | ||
| calcium carbonate | sodium phosphate | ||
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| 8)The process of changing of one element into another is called | |||
| radioactive decay | transmutation of the elements | ||
| hybridization | covalent bond formation | ||
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| 9)Chemically, baking soda is | |||
| calcium phosphate | sodium chloride | ||
| sodium bicarbonate | sodium carbonate | ||
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| 10)A saturated solution at a particular temperature | |||
| is highly coloured | is colourless | ||
| contains suspended solid particles | does not dissolve any more of the solid solute | ||
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| 11)Laundry soap is | |||
| sodium carbonate | a mixture of sodium salts of higher fatty acids of natural origin | ||
| sodium chloride | a mixture of sodium salts of synthetic sulphonic acids | ||
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| 12)Synthetic detergents are | |||
| a mixture of sodium carbonate and sodium chloride | sodium salts of fatty acids | ||
| a mixture of sodium salts of aromatic and aliphatic sulphonic acids | calcium salts of hydrochloric acids | ||
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| 13)Detergents produce lather with hard water because | |||
| they are soluble in hard water | they are colourless substances | ||
| they form sodiun carbonate with hard water | the calcium and magnesium salts of sulphonic acids are soluble in water | ||
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| 14)Lime water contains | |||
| sodium hydroxide | sodium carbonate | ||
| calcium hydroxide | calcium chloride | ||
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| 15)The ratio of different gases in air is | |||
| fixed | unknown | ||
| different from place to place | independent of industrialization of towns | ||
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