The half -life period of `._(84)Po^(210)` is 140 days.
In how many days `1 g` of this isotope is reduced to `0.25 g`?

Explanation

To solve the problem, we need to determine how many days it takes for 1 gram of Polonium-210 to decay to 0.25 grams, given that its half-life is 140 days.

### Step-by-Step Solution:

1. **Understand the Concept of Half-Life**:
The half-life of a radioactive substance is the time required for half of the substance to decay. After one half-life, half of the initial amount remains.

2. **Identify Initial and Final Amounts**:
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