At the points of intersection of `Al_(2)O_(3)` and MgO curves (A), `DeltaG^(@)` becomes zero for reaction,
`(2)/(3)Al_(2)O_(3) + 2Mg to 2MgO + 4/3 Al`
Above this point, magnesium can reduce alumina. Although thermodynamically feasible, Mg is not used to reduction of `Al_(2)O_(3)` because

Options

A. a. temperature required is very high
B. b. the yield of metal is very low
C. c. value of `DeltaG` becomes positive
D. d. magnesium is not used as reducing agent for any reaction.

Answer

A

Explanation

Temperature above the point of intersection of `Al_(2)O_(3)` and MgO to reduce `Al_(2)O_(3)` but the temperature required would be so high that the process is difficult to carry out.