Which of the following properties of white phosphorus are shared by red phosphorus ?

Options

A. It phosphorescences in air
B. It burns when heated in air
C. It dissolves in `CS_2`
D. It reacts with `NaOH` to give `PH_3`

Answer

To determine which properties of white phosphorus are shared by red phosphorus, we will analyze the given options step by step.

### Step-by-Step Solution:

1. **Understanding Phosphorescence**:
- White phosphorus exhibits phosphorescence in air, meaning it glows after being exposed to light.
- Red phosphorus does not exhibit this property.
- **Conclusion**: This property is **not shared** by both.

2. **Burning in Air**:
- Both white phosphorus and red phosphorus burn when heated in air.
- **Conclusion**: This property is **shared** by both.

3. **Solubility in Carbon Disulfide (CS2)**:
- White phosphorus is soluble in carbon disulfide, while red phosphorus is not.
- **Conclusion**: This property is **not shared** by both.

4. **Reaction with Sodium Hydroxide (NaOH)**:
- White phosphorus reacts with hot aqueous NaOH to produce phosphine (PH3).
- Red phosphorus does not react in the same way.
- **Conclusion**: This property is **not shared** by both.

### Final Answer:
The only property shared by white phosphorus and red phosphorus is that **both burn when heated in air**. Therefore, the correct answer is **Option 2**.