9. Which statements about mixtures is FALSE? Select ALL that apply. they are all mixed uniformly and have an even composition throughout
the components keep their physical properties
substances must combine in specific proportions
mixtures can be separted using physical properties.

a:

by the combination of an unlimited number of elements

the temperature of the gas, in k, not celsius.

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.