Two radioactive substances X and Y initially contain equal number of atoms. Their half-lives are 1 hour and 2 hours respectively. Calculate the ratio of their rates of disintegration after four hours.

Explanation

To solve the problem, we need to calculate the ratio of the rates of disintegration of two radioactive substances, X and Y, after 4 hours. We will use the concepts of half-life and decay constant in our calculations.

### Step-by-step Solution:

1. **Identify the Half-lives**:
- Substance X has a half-life (T1/2) of 1 hour.
- Substance Y has a half-life (T1/2) of 2 hours.

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