Which is the function of the skull

to protect the brain and to support the structure of the face, attachments is muscles

Explanation:

the function of the skull is to protect the soft and the virtual. tissues of the head, particular the brain

i look it up online and i'll tell you

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.