Which statement about human-made elements is true?

Which statement about human-made elements is true?

• A. They occur naturally in most rocks
• B. They are always stable
• C. They are synthetic and produced in laboratories
• D. They cannot be produced via nuclear reactions

Answer: (C)

Human-made elements are synthetic and produced in laboratories. These elements aren’t found in Earth’s rocks in any significant amounts, and most of them are unstable and radioactive, decaying away over time. They’re created in lab settings by nuclear reactions—such as bombarding target nuclei with high-energy particles in accelerators or by neutron irradiation in nuclear reactors—which pushes the nucleus to a higher atomic number. That’s why the true statement is that they are synthetic and produced in laboratories. The other options don’t fit because these elements are not naturally abundant in rocks, they are not all stable, and they can be produced via nuclear reactions.

Human-made elements are synthetic and produced in laboratories. These elements aren’t found in Earth’s rocks in any significant amounts, and most of them are unstable and radioactive, decaying away over time. They’re created in lab settings by nuclear reactions—such as bombarding target nuclei with high-energy particles in accelerators or by neutron irradiation in nuclear reactors—which pushes the nucleus to a higher atomic number. That’s why the true statement is that they are synthetic and produced in laboratories. The other options don’t fit because these elements are not naturally abundant in rocks, they are not all stable, and they can be produced via nuclear reactions.