Hello there!
To determine the fraction of the hydrogen atom's mass that is in the nucleus, we have to keep in mind that
a Hydrogen atom has 1 proton and 1 electron.
Protons are in the nucleus while electrons are in electron shells surrounding the nucleus.
The mass of the nucleus will be equal to the mass of 1 proton and we can express the fraction as follows:

So, the fraction of the hydrogen atom's mass that is in the nucleus is
0,9995. That means that almost all the mass of this atom is at the nucleus.
Have a nice day!
Answer:
Ionic Compounds have high boiling and melting points as they're very strong and require a lot of energy to break. The electrostatic forces of attraction between oppositely charged ions lead to the formation of ions. Ionic compounds form crystals. These compounds are brittle and break into small pieces easily.
Explanation:
The change from figure one to figure two was most likely caused by erosion. Erosion is the process of something being eroded by wind, water, or other natural agents.