Which of the following descriptions correctly describes the structure of an atom?

• A. An atom consists of a dense nucleus containing protons and neutrons, surrounded by electrons in a cloud.
• B. An atom is a solid sphere with protons, neutrons, and electrons evenly distributed throughout.
• C. An atom is made up of only electrons and protons, with no neutrons present.
• D. An atom has a nucleus composed solely of electrons, with protons and neutrons orbiting around it.

Answer: (A)

Verified step by step guidance

1. Recall the basic structure of an atom: it consists of a central nucleus and electrons surrounding it.
2. Understand that the nucleus contains protons, which are positively charged, and neutrons, which have no charge; these particles are densely packed together.
3. Recognize that electrons are negatively charged particles that occupy a region around the nucleus often described as an electron cloud, not fixed orbits.
4. Eliminate incorrect descriptions: atoms are not solid spheres with evenly distributed particles, nor do they lack neutrons, nor do electrons form the nucleus.
5. Conclude that the correct description is that an atom consists of a dense nucleus containing protons and neutrons, surrounded by electrons in a cloud.