Answer the following question:
A mining company extracts three metals X, Y and Z from the earth’s crust. Metal X occurs in the free state and does not react with air or moisture. Metal Y occurs as sulphide/oxide ores and is extracted using carbon, while metal Z is highly reactive, reacts with water, and is extracted only by electrolysis. The ore of metal Y contains sand and rocky impurities.
i. Which observation confirms that metal Z belongs to the top of the reactivity series?
ii. Which extraction method is suitable for metal Z?