Rusting of iron is a `"_____"` change .(periodic , non- periodic , desirable)

Answer

To determine the type of change that rusting of iron represents, we can follow these steps:

### Step 1: Understand the process of rusting
Rusting is a chemical process that occurs when iron reacts with oxygen in the presence of moisture (water). This reaction forms iron oxide, commonly known as rust.

### Step 2: Identify the types of changes
There are different types of changes:
- **Periodic Change**: Changes that occur at regular intervals (e.g., seasons).
- **Non-Periodic Change**: Changes that do not occur at regular intervals and can happen at any time (e.g., rusting of iron).
- **Desirable Change**: Changes that are beneficial or wanted (e.g., cooking food).

### Step 3: Analyze rusting
Rusting does not happen at regular intervals; it occurs when iron is exposed to moisture and air. Therefore, it does not fit the definition of a periodic change.

### Step 4: Determine if it is desirable
Rusting is generally considered undesirable because it leads to the deterioration of iron and steel, causing damage to structures and objects made of these materials.

### Conclusion
Since rusting is a change that occurs irregularly and is not beneficial, we conclude that rusting of iron is a **non-periodic** change.

### Final Answer
Rusting of iron is a **non-periodic** change.

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