It means that you consider the elements as a list organized by atomic number, the property is seen to repeat over and over as you move through that list.
Answer:
Heat is transferred by the hot air or water moving to a cooler area. The elements rotate in circular motions, giving the geyser pressure.
As per Bernuolli's Theorem total energy per unit mass is given as

now from above equation




now by above equation


Part B)
Now energy per unit weight



Answer:
In most materials, as heat energy is absorbed, the density decreases. IF a certain object is heated, it might appear bigger than usual because it expands as the molecules inside moves faster than usual. However the mass of it stays the same while the density decreases.
Because cool air rises and warm air falls, so if you wanted the cooler air, you would need to go to higher elevation