Which of the following statements about stable isotopes is correct?

• A. Stable isotopes have the same number of neutrons as protons.
• B. Stable isotopes do not undergo radioactive decay.
• C. Stable isotopes always have a mass number of 12.
• D. Stable isotopes emit alpha particles over time.

Answer: (B)

Verified step by step guidance

1. Understand what isotopes are: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
2. Recall the definition of stable isotopes: Stable isotopes are those that do not undergo radioactive decay, meaning they remain unchanged over time.
3. Evaluate the first statement: 'Stable isotopes have the same number of neutrons as protons.' This is generally not true because isotopes differ in neutron number; stability is not defined by equal numbers of protons and neutrons.
4. Evaluate the third statement: 'Stable isotopes always have a mass number of 12.' This is incorrect because stable isotopes can have various mass numbers depending on the element and its isotopes.
5. Evaluate the fourth statement: 'Stable isotopes emit alpha particles over time.' This is false because emission of alpha particles is a characteristic of radioactive decay, which stable isotopes do not undergo.