Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
In the electrolysis of alumina to obtain aluminium metal, cryolite is added mainly to
ChemistryGeneral Principles and Processes of Isolation of MetalsJEE MainJEE Main 2012 (12 May Online)
Options:
  • A
    lower the melting point of alumina
  • B
    dissolve alumina in molten cryolite
  • C
    remove the impurities of alumina
  • D
    increase the electrical conductivity
Solution:
1644 Upvotes Verified Answer
The correct answer is:
lower the melting point of alumina
Fused alumina $\left(\mathrm{Al}_2 \mathrm{O}_3\right)$ is a bad conductor of electricity. Therefore, cryolite $\left(\mathrm{Na}_3 \mathrm{AlF}_6\right)$ and fluorspar $\left(\mathrm{CaF}_2\right)$ 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 $1140 \mathrm{~K}$.

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.