What are pictometers?

Answer 1

Do you mean a Pycnometer. This is a small glass bottle apparatus and is used to determine relative density. Mainly used to determine relative density of a liquid.

But may also determine the relative density of a powder, if you have access to a liquid in which the powder is insoluble.

In either case, the determination is made by simple weighing.

Answer 2

Oh, dude, pictometers are basically just a unit of measurement in the metric system. They're like super tiny, like even smaller than a nanometer. So, if you ever need to measure something really, really small, you can whip out the pictometers and impress all your science friends.