You have a 10.0 g sample of gallium-68. Half of it decays in 68.3 minutes. How much will be left after two half-lives? Make sure to round to the correct number of significant figures and use units (g)

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.  

i think the answer is terrae but not 100 percent sure. ▓▬▬ §

c. electrical charges of ionic bonds.