Explain why cobalt choride acts as a humidity indicator.

Explanation

### Step-by-Step Solution:

1. **Understanding Cobalt Chloride**:
Cobalt chloride is a chemical compound with the formula CoCl2. It can exist in two forms: anhydrous (without water) and hydrated (with water).

2. **Color of Anhydrous Cobalt Chloride**:
The anhydrous form of cobalt chloride is blue in color. This is important because the color change is what allows it to indicate humidity.

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