Answer:
Conductivity probe
Explanation:
The Conductivity Probe consists of two electrodes(also referred to as probes)or an electrode and a wall vessel where the material in the vessel completes the circuit as the level rises in the vessel.
It is used in measuring solution conductivity or total ionic concentration of aqueous samples.
Are you referring to the fact that water is a compound while hydrogen is an element? If I'm wrong just comment and clarify and I can edit it, I don't even know what kind of unit you're in. :)
Answer:
At a sunny day at the beach, the top of the sand is warm. The radiation from the Sun heats up the surface of the sand, but sand has a low thermal conductivity, so this energy stays at the surface of the sand.