Heliocentric and geocentric

me on this. i don't know what i'm supposed to do and im struggling

Explanation:

heliocentric means having the sun in the middle/center in the solar system

geocentric means having the earth in the middle/center in the solar system

therefore your answers are:

the planets orbit the sun.

in 1543, Nicolaus Copernicus proposed the theory.

the evidence that led people to believe this was when Galileo observed that four moons orbited around Jupiter. in other words, heliocentric.

most of the stars are located in the milky way galaxy.

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.