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Chemistry |
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| 106)The substance most commonly used as a food preservative is | |||
| acetic acid | tartaric acid | ||
| benzoic acid | sodium carbonate | ||
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| 107)The reagent that bleaches the colour of a fabric is | |||
| sulphur dioxide | sodium chloride | ||
| carbon dioxide | sulphur trioxide | ||
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| 108)A chemical reaction that place with the evolution of heat is called a/an | |||
| endothermic reaction | reversible reaction | ||
| exothermic reaction | thermal reaction | ||
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| 109)The process in which a solid substance, on being heated, changes directly into the gaseous form is known as | |||
| dissociation | dissolution | ||
| evaporation | sublimation | ||
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| 110)The smallest possible unit of a chemical compound is | |||
| atom | electron | ||
| molecule | proton | ||
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| 111)Silver halides are used in photographic plates because they are | |||
| colourless | oxidised in air | ||
| readily reduced by light | easily soluble in hypo solution | ||
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| 112)Hypo, used in photography, is chemically | |||
| sodium thiosulphate | silver bromide | ||
| silver nitrate | sodium phosphate | ||
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| 113)It is not advisable to sleep under a tree at night because trees release _______ at night | |||
| oxygen | carbon dioxide | ||
| nitrogen | sulphur dioxide | ||
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| 114)Cinnabar is an ore of | |||
| iron | copper | ||
| lead | mercury | ||
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| 115)The crystalline form of silica used in scientific apparatus for passing ultraviolet light is called | |||
| pyrex glass | soda glass | ||
| quartz glass | corning glass | ||
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| 116)Camphor can easily be purified by the process of | |||
| sublimation | crystallisation | ||
| sedimentation | distillation | ||
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| 117)The gas used for artificial ripening of green fruit is | |||
| carbon dioxide | acetylene | ||
| ethane | ethylene | ||
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| 118)The most commonly used metal in the pure form or as an alloy in domestic appliances is | |||
| iron | copper | ||
| aluminium | zinc | ||
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| 119)The purity of primary gold is | |||
| 10 carat | 16 carat | ||
| 24 carat | 32 carat | ||
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| 120)Tetraethyl lead (TEL) is added to petrol to | |||
| increase boiling point | increase flash point | ||
| prevent freezing | increase anti-knocking rating | ||
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