You decide to seek your fortune as a metal supplier. The problem is you cant decide which metal to specialise in. You know that you will have to extract the metal from the earth's crust

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.  

bcde is the incorrect answer it is a

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante