Question

an atom has 8 protons, 8 neutrons, and 8 electrons. another isotope of the same element might have mass number 16, atomic number 7. 10 neutrons. 9 protons. 7 electrons. all of the above. part i radioactive decay is likely to occur when an atom has too many neutrons. protons break into neutrons and electrons. an electron hits the nucleus. an atom has too many electrons. atoms collide with one another.

Explanation:

1. Isotope question: Isotopes of an element have the same number of protons (which defines the atomic number), but different numbers of neutrons. The given atom has 8 protons. So, an isotope could have a different number of neutrons. Options with different proton or electron numbers are incorrect as they would be different elements or ions. Also, the atomic - number cannot change for isotopes of the same element.
2. Radioactive decay question: Radioactive decay often occurs when an atom has an unstable nucleus, which can be due to having too many neutrons. Protons do not break into neutrons and electrons in the context of common radioactive - decay processes described here. An electron hitting the nucleus is not a common cause of decay, and having too many electrons or atoms colliding with one another is not the main cause of radioactive decay.

Answer:

1. 10 neutrons
2. an atom has too many neutrons