Because alcohol expands over small temp changes, hence while a vial of it is used in sprinklers as the stop plug; the room gets hotter, the plug shatters.
the cathode is where reduction occurs!
Alkali Metals (Group 1) elements experience an increase in the vigour of their reaction in water as they go down the group (as the atomic number increase). As such the most reactive Alkali Metal would be
FRANCIUM, which is at the base of Group One.
Quite frankly, you do not want Francium to react with water- that's a huge explosion on your hand.
Ultraviolet rays has the most energy