On a smooth horizontal floor an object

Aprisoner is forced to go into one of three rooms, but he can choose which room. the first room is ablaze with fire. the second one is rigged with explosives that will go off as soon as he enters. the third contains a pair of lions who haven't eaten in years. which room should he choose to survive?

Smallest intensity of a stimulus that you can detect 50 percent of the time is

How are positive ions different from neutral atoms