A Level Physics Practice Exam

The correct choice is approximately one ten thousandth for the relative size of the nucleus compared to the entire atom.

To understand this, consider that the nucleus, which contains protons and neutrons, is significantly smaller than the atom as a whole. The radius of a nucleus is typically on the order of 1 femtometer (10^-15 meters), while the radius of an atom is around 100 picometers (10^-10 meters). When you calculate the ratio of the size of the nucleus to the size of the atom, it results in a value of about 1/10000, confirming that the nucleus occupies a minute fraction of the total volume of the atom.

This substantial difference in scale is crucial to understanding atomic structure; most of an atom's volume is empty space surrounding the nucleus, where the electron cloud exists. This context highlights the major contrast between the nucleus and the atom as a whole, reinforcing why the choice indicating one ten thousandth accurately represents their relative sizes.