PH is what they call measure of the concentration<span> of hydrogen ions in a solution. Strong </span>acids <span>like hydrochloric </span>acid<span> at the sort of </span>concentrations<span> you normally use in the lab have a pH around 0 to 1. The lower the pH, the higher the </span>concentration<span> of hydrogen ions in the solution. </span>
This demonstration is most likely trying to show you potential energy. The rock is heavier than the pebble and will therefore displace more sand upon impact showing that the rock stores more potential energy than the pebble does when they are elevated to the same height (in this case the height is the height of the table).
This makes sense since potential energy is equal to mass times the acceleration due to gravity times height (PE=mgh) and the only thing that is changing is the mass of the object being suspended which means that the heavier object (the rock) will have more potential energy.
I hope this helps. Let me know if anything is unclear.
Rutherford theorized that atoms have their charge concentrated in a very small nucleus.
This was famous Rutherford's Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles (helium atom particles, consist of two protons and two neutrons).
Rutherford observed the deflection of alpha particles on the photographic film and notice that most of alpha particles passed straight through foil.
That is different from Plum Pudding model, because it shows that most of the atom is empty space.
According to Rutherford model of the atom:
1) Atoms have their charge concentrated in a very small nucleus.
2) Major space in an atom is empty.
3) Atoms nucleus is surrounded by negatively charged particles called electrons.
4) An atom is electrically neutral.
