A substance has a half life of 6000 years. how much of the substance will be radioactive after a total of 12,000 years a. half of the original substance
b. one fourth of the orgininal substance
c. all of the original substance
d. none of the orgininal substance

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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.  

the answer is minerals.