If the amount of a radioactive substance is increased four times then how many times will the number of atoms disintegrating per unit time be increased ?

Explanation

To solve the problem, we need to understand the relationship between the amount of a radioactive substance and the rate of disintegration (decay rate).

### Step-by-Step Solution:

1. **Define the Decay Rate**:
The decay rate (r) is defined as the number of disintegrations per unit time. It can be expressed mathematically as:
\[
r = \lambda N
...