Your answer is going to be a Scanning Tunneling microscope, I hope this helps!!
They discovered this since S waves don’t travel through the earth but P waves do. P waves tend to travel faster than S waves in speed, 1&14km/s vs 1&8km/s
Explanation:
Things that float=paper,plastic bottle,rubber, polythene bag, balloon
Things that sinks =needle,stone,spoon,pen,soap
It would be S - 35 because people made the short form of each element to make it easier to understand and it is also used all around the world and 35 is the atomic number. Hope this helps ;)