(i)The roasted ore is heated with concentrated. Sodium hydroxide under pressure, Aluminium oxide being amphoteric dissolves in Sodium hydroxide.
(ii) Iron (III) oxide/ Iron hydroxide does not dissolve (insoluble in NaOH)
(iii) Cryolite lowers the melting point of alumina.
sharon kalunda answered the question on May 21, 2019 at 09:02
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