Arock formed with 1,000 atoms of a radioactive parent element, but only contains 12.5% of its original radioactive parent atoms today. if the half-life is 1,000,000 years, how old is the rock? (ess 4.6)

by cartels in other countries, shipped by air, mail, or land. i cant really see your answer choices : /

they are both synthetic elements

explanation:

d

am i too late?

explanation:

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.

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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.