For each of the following, state one phenomenon in which :
(i) particles behave like waves. (ii) waves behave like particles.

Explanation

To solve the question, we need to identify one phenomenon for each of the two scenarios: (i) where particles behave like waves, and (ii) where waves behave like particles.

### Step-by-Step Solution

1. **Identify a phenomenon where particles behave like waves:**
- The phenomenon we can use is the **Davisson-Germer Experiment**. This experiment demonstrated that electrons, which are particles, can exhibit wave-like behavior.
- In this experiment, an electron beam is directed at a nickel crystal. When the electrons hit the crystal, they scatter and create an interference pattern, which is a characteristic of waves. This interference pattern indicates that the electrons are behaving like waves.

...