Extraction of Metals - Result Question 49
####49. In the electrolysis of alumina, cryolite is added to
$(1986,1 M)$
(a) lower the melting point of alumina
(b) increase the electrical conductivity
(c) minimise the anode effect
(d) remove impurities from alumina
Assertion and Reason
Read the following questions and answer as per the direction given below:
(a) Statement I is correct; Statement II is correct; Statement II is the correct explanation of Statement I.
(b) Statement I is correct; Statement II is correct; Statement II is not the correct explanation of Statement I.
(c) Statement I is correct; Statement II is incorrect.
(d) Statement I is incorrect; Statement II is true.
Show Answer
Solution:
- Alumina $\left(Al _2 O _3\right)$ has very high melting point and it is poor conductor of electricity. Both these factors posses difficulty in electrolysis of molten alumina.
Cryolite, $Na _3 AlF _6$, when mixed with alumina, lowers melting point as well as improve electrical conductivity, hence helps in electrolysis of $Al _2 O _3$.
