Radium `226` is found to have a decay constant of `1.36 xx10^(-11)` Bq.
Determine its half-life in years. If a `200 g` sample of radium was taken in `1902`, how much of it will remain a hundered years later?

Explanation

To solve the problem step by step, we will break it down into two parts: finding the half-life of Radium-226 and determining the amount remaining after 100 years.

### Part A: Finding the Half-Life of Radium-226

1. **Identify the decay constant (λ)**:
- Given: λ = \(1.36 \times 10^{-11}\) Bq.

2. **Use the formula for half-life (t_half)**:
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