Tritium has a half life of 12.5 years against beta decay. What fraction of a sample of pure tritium will remain undecayed after 25 years?

Explanation

To solve the problem of determining the fraction of a sample of pure tritium that remains undecayed after 25 years, we can follow these steps:

### Step 1: Identify the given values
- Half-life of tritium (\( t_{1/2} \)): 12.5 years
- Time elapsed (\( t \)): 25 years

### Step 2: Calculate the number of half-lives that have passed
To find out how many half-lives fit into the total time elapsed, we use the formula:
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