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General Principles and processes of Isolation of Elements
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In the electrolysis of alumina to obtain aluminium metal, cryolite is added mainly to
A
lower the melting point of alumina
B
dissolve alumina in molten cryolite
C
remove the impurities of alumina
D
increase the electrical conductivity
(AIEEE-2012)
Solution
Fused alumina $(Al_2O_3)$ is a bad conductor of electricity. Therefore, cryolite $(Na_3AlF_6)$ and fluorspar $(CaF_2)$ are added to purified alumina which not only make alumina a good conductor of electricity but also reduce the melting point of the mixture to around $1140\, K$.
Standard 12
Chemistry
Similar Questions
Correct match the List- $I$ with List- $II$
| List- $I$ | List- $II$ |
| $(P)\, [M(CN)_2]^-$ | $(1)$ $Ni$ (during refining of metal) |
| $(Q)\, [M(CO)_4]$ | $(2)\, Ti$ (during refining of metal) |
| $(R)\, MI_4$ | $(3)\, Pb$ (during roasting of ore) |
| $(S)\, MO$ | $(4)\, Ag$ (during leaching of ore) |
normal
