Phosphrous undergoes slow combustion and glows in dark. The process is called

Options

A. Photochemical change
B. Chemiluminescence
C. Flourescene
D. Phosphorescene

Answer

To solve the question regarding the process by which phosphorus undergoes slow combustion and glows in the dark, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Properties of Phosphorus**:
- Phosphorus is a non-metal and belongs to the P-block of the periodic table. It has the symbol "P" and atomic number 15.

2. **Identifying the Phenomenon**:
- When phosphorus undergoes slow combustion, it emits light. This light emission occurs without a significant increase in temperature, which is characteristic of certain processes.

3. **Defining the Process**:
- The specific process by which phosphorus glows in the dark due to slow combustion is known as "phosphorescence." This is different from fluorescence, where the light emission stops almost immediately after the excitation source is removed.

4. **Selecting the Correct Option**:
- Given the options provided, the correct term for the phenomenon where phosphorus glows in the dark due to slow combustion is "phosphorescence." Therefore, the answer is option D.

5. **Applications of Phosphorescence**:
- Phosphorescence has practical applications, including its use in glow-in-the-dark toys, paints, and clock dials.

### Final Answer:
The process by which phosphorus undergoes slow combustion and glows in the dark is called **phosphorescence** (option D).

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