How many of the following are not a colloid? Chlorophyll, Smoke, Ruby glass and Milk

Explanation

To determine how many of the given substances are not colloids, we need to analyze each substance: chlorophyll, smoke, ruby glass, and milk.

### Step 1: Define Colloids
Colloids are homogeneous non-crystalline substances consisting of large molecules or ultramicroscopic particles of one substance dispersed in another substance. They can be classified based on the states of the dispersed phase and the dispersion medium.

### Step 2: Analyze Each Substance
1. **Chlorophyll**:
- Chlorophyll is a pigment found in plants, primarily responsible for the absorption of light during photosynthesis. It is not a colloid; it is a solution or a suspension in the context of its natural state in plants.

2. **Smoke**:
- Smoke is a colloidal solution of solid particles dispersed in a gas. It is classified as an aerosol, where the dispersion medium is gas and the dispersed phase is solid. Therefore, smoke is a colloid.

3. **Ruby Glass**:
- Ruby glass contains colloidal gold particles that give it its characteristic color. The gold particles are dispersed in the glass matrix, making ruby glass a colloid.

4. **Milk**:
- Milk is an emulsion, which is a type of colloid where fat globules are dispersed in water. Therefore, milk is also a colloid.

### Step 3: Conclusion
From the analysis:
- Chlorophyll is **not** a colloid.
- Smoke, ruby glass, and milk are colloids.

Thus, the number of substances that are not colloids is **1** (only chlorophyll).

### Final Answer
**1**

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