In the Hoope's process for refining of aluminium, the fused materials form three different layers and they remain separated during electrolysis also. This is because:
Correct answer: D. Both B and C
- A. There is special arrangement in the cell to keep the layers separate.
- B. The three layers have different densities.
- C. The upper layer is kept attracted by the cathode and the lower layer is kept attracted by the anode.
- D. Both B and C
Explanation
Option D is correct. The three layers have different densities. In the Hoope's process for refining of aluminium, the fused materials form three different layers: Upper layer: This layer is composed of pure aluminium. It has the highest density and floats on the surface of the electrolyte. Middle layer: This layer is composed of a mixture of aluminium oxide and aluminium. It has a lower density than the upper layer but higher than the lower layer. Lower layer: This layer is composed of aluminium oxide and other impurities. It has the lowest density and sinks to the bottom of the electrolyte. Electrolysis: The impure aluminium is melted and electrolyzed in a bath of cryolite. The aluminium ions in the electrolyte are attracted to the cathode, where they are reduced to pure aluminium metal. The impurities in the electrolyte are attracted to the anode, where they are oxidized and removed from the electrolyte.
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The s and p blocks are studied through their valence-shell configurations, periodic trends and characteristic chemical properties. Work covers the reactions of Group I and Group II elements, the behaviour of Group IV elements, and how atomic size, ionization energy, electronegativity and metallic character change across periods and down groups.
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