Separate the pennies you have into two groups: one group with pennies dated before 1982 and the other with pennies dated after 1982. compare the two groups. record any similarities or differences in size or appearance that you notice between the two groups.

la respuesta es si te gusta hacer lo que siempre haces cuando nunca ves a alguien en el espejo porque sabes que no siempre están ahí.

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.