Atomic and nuclear scales: identify the correct statement about ions, sizes, and stable nucleus composition.

Introduction / Context:
Understanding orders of magnitude for atomic and nuclear dimensions, as well as correct ion definitions, is foundational in chemistry and nuclear engineering. These quantities explain why atoms are largely empty space compared to their dense nuclei and clarify basic terminology for charged species.

Given Data / Assumptions:

• Nuclear radii are orders of magnitude smaller than atomic sizes.
• Cations and anions form via electron loss or gain, respectively.
• Stable nuclei have varying proton-to-neutron ratios depending on mass number.

Concept / Approach:
Atomic sizes are on the order of angstroms, about 10^-8 cm. Nuclear radii are roughly femtometre scale, often quoted around 10^-13 to 10^-12 cm depending on the nucleus; as an order-of-magnitude statement, 10^-12 cm is an acceptable scale indicator in many textbooks. Ion formation is defined by electron transfer: loss yields cations (positive), gain yields anions (negative). The proton-to-neutron ratio for stability is not fixed at 2:1; it is near 1:1 for light nuclei and shifts for heavier nuclei.

Step-by-Step Solution:
Compare scales: atomic size (~10^-8 cm) vs nuclear size (~10^-12 to 10^-13 cm).Evaluate ion statements: loss → cation (not negative ion); gain → anion (not cation).Check stability ratio claim: no universal 2:1 rule; varies with mass number.Confirm that removing electrons does not change nucleon count (protons + neutrons) in the nucleus.

Verification / Alternative check:
Introductory physical chemistry and nuclear physics references consistently present these orders of magnitude and definitions, supporting the correctness of the size comparison statement.

Why Other Options Are Wrong:
Loss → negative ions: incorrect; loss gives positive ions.Gain → cations: incorrect; gain gives anions.Proton-to-neutron ratio 2:1: not general; varies by element and mass number.Electron removal changes nucleons: false; nucleons are unaffected by electron transfer.

Common Pitfalls:
Mixing up signs of ions and conflating atomic radius scales with nuclear radius scales. Keep powers of ten explicit to avoid confusion.

Final Answer:
A typical nuclear radius is about 10^-12 cm, while atomic size is about 10^-8 cm.