The `I-128` has no therapeutic value because

Options

A. It is poisonous
B. It is very stable
C. It decays quickly and loses radioactivity.
D. It is not radioactive

Answer

To understand why Iodine-128 (I-128) has no therapeutic value, we can break down the reasoning into clear steps:

### Step-by-Step Solution:

1. **Understanding Iodine-128**:
- I-128 is a radioactive isotope of iodine.

2. **Half-Life Concept**:
- The half-life of I-128 is approximately 24.99 minutes. This means that in about 25 minutes, half of the I-128 will have decayed into other elements or isotopes.

3. **Implications of a Short Half-Life**:
- A short half-life indicates that the isotope is highly unstable. It decays rapidly, meaning that a significant amount of the substance will not be available for use after a short period.

4. **Therapeutic Use of Isotopes**:
- For an isotope to be useful in medical therapies, it needs to have a longer half-life so that it remains active long enough to be effective in treatment.

5. **Decay and Availability**:
- Since I-128 decays quickly (in about 25 minutes, it will have lost 50% of its activity), it will not be present in sufficient quantities for therapeutic applications after a short duration.

6. **Conclusion**:
- Therefore, due to its very short half-life, I-128 cannot be used for therapeutic purposes as it decays too quickly and loses its radioactivity.

### Final Answer:
Iodine-128 has no therapeutic value because it decays quickly and loses its reactivity.

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