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Chemistry

1)Pure water can be obtained from sea water by the process of
filtration distillation
evaporation fractional distillation
Answer :

2)Common salt can be obtained from sea water by the process of
sublimation filtration
evaporation crystallisation
Answer :

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
Answer :

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
Answer :

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
Answer :

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