Besides radium, what other world-altering discoveries can you think of that both led to advancement, and also tragedy?*

What produces wave a)sound b) heats c)transfer of energy d)vibrations

What is the measured amount of a product obtained from a chemical reaction?

How many lone pairs of electrons are on the central atom of no3- and what is the molecular shape? one, trigonal planar zero, trigonal pyramidal zero, trigonal planar one, tetrahedral one, trigonal pyramidal