Which of the following about dalton's theory of matter is true?
a.) atoms can be created
b.) atoms of the same element have the same mass
c.) compounds formed from two elements will not always have the same proportions
d.) atoms cannot be divided into smaller parts

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.  

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.