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Aluminium is stable in air and water inspite of the fact that it is reactive metal. The reason is that a thin film of its oxide, if formed on its surface which makes it passive for further attack. The layer is so useful that in industry, it is purposely deposited by an electrolytric process called anodizing. Reaction of aluminium with oxygen is highyl exothermic and is called thermite reaction2Al(s)+(3)/(2)O_(2)(g)rarr Al_(2)O_(3)(s), Delta H=-1670 kJThermite reaction finds applications in the metallurgical extraction of many metals from their oxides and for welding of metals. The drawback is that to start the reaction, high temperature is required for which an ignition mixture is used.Anodised aluminium is

Answer» <html><body><p>Al obtained at <a href="https://interviewquestions.tuteehub.com/tag/anode-876537" style="font-weight:bold;" target="_blank" title="Click to know more about ANODE">ANODE</a> <br/>Al <a href="https://interviewquestions.tuteehub.com/tag/prepared-1163605" style="font-weight:bold;" target="_blank" title="Click to know more about PREPARED">PREPARED</a> electrolytically<br/>Alloy of Al <a href="https://interviewquestions.tuteehub.com/tag/containing-2035611" style="font-weight:bold;" target="_blank" title="Click to know more about CONTAINING">CONTAINING</a> <a href="https://interviewquestions.tuteehub.com/tag/95-342378" style="font-weight:bold;" target="_blank" title="Click to know more about 95">95</a>% Al <br/>Al electrolytically <a href="https://interviewquestions.tuteehub.com/tag/coated-920548" style="font-weight:bold;" target="_blank" title="Click to know more about COATED">COATED</a> with `Al_(2)O_(3)`</p>Solution :Anodised aluminium is Al electrolytically coated with `Al_(2)O_(3)`</body></html>


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