The half life of Cobalt–60 is –
**Core Concept**
The question tests knowledge of **radioactive isotopes** and their **half-lives**, specifically focusing on **Cobalt-60**, a synthetic radioactive isotope of cobalt with applications in medicine, industry, and research.
**Why the Correct Answer is Right**
Cobalt-60 has a well-documented **half-life** of approximately 5.2713 years. This is the time required for half of the atoms in a sample of Cobalt-60 to undergo **radioactive decay**, emitting **gamma radiation**. Understanding the half-life of radioactive isotopes is crucial for their safe handling and application in medical treatments, such as **cancer therapy**.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not match the known half-life of Cobalt-60.
**Option B:** Similarly, this option is also incorrect as it does not align with the established half-life of Cobalt-60.
**Option D:** This option is incorrect as well, given that the half-life of Cobalt-60 is not in this range.
**Clinical Pearl / High-Yield Fact**
Remembering the half-life of Cobalt-60 is important for **radiation safety** and understanding the duration for which radioactive materials remain hazardous. This knowledge is crucial in **nuclear medicine** and **radiation oncology**.
**Correct Answer:** C. 5.27 years