Density = mass / volume
Density = (78g) / (23cm^3)
Density = 3.4g/cm^3
Making an atom or a virus structure
Sodium lends 1 electron.
Phosphorus borrows 3 electrons.
Potassium lends one electron.
Oxygen borrows 2 electrons.
Iodine borrows one electron.
Cesium lends 1 electron.
Bromine borrows 1 electron.
Sulfur borrows 2 electrons.
And magnesium lends 2 electrons.
There are many simple ways to prevent erosion. One of the simplest forms of preventing erosion is with vegetation and by establishing root systems that hold the soil together. You can also use geotextiles, fertilizers and also build retainer walls to keep the soil intact and prevent erosion.
In magnet I believe nickle is used most often