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InterviewSolution
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19) Give reasons:i) Concentrated HNO3 can be transported iraluminium container.ii) Graphite is used as a lubricant.ili) Diamond is used as an abrasive.iv) Aluminium utensils should not be kept in waterovernight. |
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Answer» i. ConcentatedHNO3renders Al passive due to the formation of thin oxide coating on the surface of the metal which prevents further reaction. thereforeconc HNO3 can be transportedin Alcontainers ii. Graphite is used as a lubricantdue to its slippery nature.Graphitehas layers of carbon atoms, with weak forces, residing in between its layers because of which itisquite slippery. iii. Because diamonds are very hard (ten on the Mohs scale) they are often used as an abrasive. Most industrial diamonds are used for these purposes. Small particles of diamond are embedded insaw blades, drill bits and grinding wheels for the purpose ofcutting,drillingor grinding hard materials. Aluminium utensils should not be kept in water overnightbecausealuminiumis readily corroded bywater. |
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