List and describe the four layers of the Earth.

Broadly speaking, the Earth has four layers: the solid crust on the outside, the mantle and the core -- split between the outer core and the inner core. Broadly speaking, the Earth has four layers: the solid crust on the outside, the mantle and the core — split between the outer core and the inner core.

Explanation:

120,630,890

step-by-step explanation:

110+10=120,620+10=630,880+10=890

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.