The reduction of ore to particular metal mainly depends on position of metal in the activity series.
Extraction of metals at the top of activity series. .
1) Simple chemical reduction methods like heating with C, CO etc., to reduce the ores of the metals are not possible with metals like K, Na, Ca, Mg and Al.
2) The temperature required for the reduction is too high and more expensive.
3) The only method used to extract these metals is by electrolysis of their fused compounds.