`._(11)Na^(24)` half-life is 15 hours. On heating it will

Options

A. Reduce
B. Remain unchanged
C. Depend on temperature
D. Become double

Explanation

To solve the question regarding the behavior of sodium-24 (Na-24) when heated, we need to analyze the properties of radioactive decay and the effect of temperature on it.

### Step-by-Step Solution:

1. **Understand the Half-Life Concept**:
The half-life of a radioactive isotope is the time required for half of the radioactive atoms in a sample to decay. For Na-24, the half-life is given as 15 hours.

2. **Radioactive Decay**:
The decay of radioactive isotopes is a random process and is characterized by a decay constant (λ). The decay constant is related to the half-life (T₁/₂) by the formula:
\[ \lambda = \frac{\ln(2)}{T_{1/2}} \]
For Na-24, we can calculate λ:
\[ \lambda = \frac{\ln(2)}{15 \text{ hours}} \approx 0.0462 \text{ hours}^{-1} \]

3. **Effect of Heating on Radioactive Decay**:
It is important to note that the rate of radioactive decay is not affected by external conditions such as temperature. This means that even if Na-24 is heated, its half-life remains the same, and the decay process continues at the same rate.

4. **Conclusion**:
Therefore, when Na-24 is heated, the half-life does not change, and the amount of Na-24 will decay at the same rate as it would at a lower temperature. The correct conclusion is that heating Na-24 will not affect its half-life or decay rate.

### Final Answer:
On heating, Na-24 will remain unchanged in terms of its half-life and decay rate.

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