aluminium metal cannot be produced by electrolysis of aqueous solution of aluminium salt.give reason.

Aluminum is the most abundant metallic element in the earth's crust present in the rocks.  However, its isolation is very difficult and expensive to accomplish by purely chemical means, as evidenced by the high E° (–1.66 v) of the Al3+/Al couple. For the same reason, aluminum cannot be isolated by electrolysis of aqueous solutions of its compounds, since the water would be electrolyzed and if you have ever tried to melt a rock, you will appreciate the difficulty of electrolyzing a molten aluminum ore. Aluminum was in fact considered an exotic and costly metal.