Question

what is an atomic nucleus?
the outer part of an atom in which electrons move
the outer part of an atom in which neutrons move
the central part of an atom, composed of protons and neutrons
the central part of an atom, composed of protons and electrons

Explanation:

To determine the correct definition of an atomic nucleus, we recall atomic structure: an atom has a central nucleus and an electron cloud (outer part) with electrons. The nucleus contains protons (positive charge) and neutrons (neutral), while electrons are in the outer regions.

• The first option is incorrect as the outer part with electrons is the electron cloud, not the nucleus.
• The second option is incorrect because neutrons are in the nucleus, not moving in the outer part, and the outer part does not have neutrons moving there.
• The fourth option is incorrect because electrons are not in the nucleus; they are in the electron cloud.
• The third option correctly states the nucleus is the central part of an atom, composed of protons and neutrons.

Answer:

C. the central part of an atom, composed of protons and neutrons