The correct answer is option 4. Red phosphorus.
Let us look at each option carefully:
1. White phosphorus:
White phosphorus is highly reactive and can spontaneously catch fire in the presence of air. It is often stored underwater or in inert gases to prevent its exposure to oxygen.
2. Alpha-black phosphorus:
Alpha-black phosphorus is another allotrope that is more stable than white phosphorus but can still react with oxygen and catch fire, though it is less reactive than the white form.
3. Beta-black phosphorus:
Similar to alpha-black phosphorus, beta-black phosphorus is also relatively reactive and can catch fire in the presence of oxygen.
4. Red phosphorus:
Red phosphorus is the least reactive allotrope of phosphorus. It is stable and does not catch fire easily. Red phosphorus is used in safety matches, where it can be ignited only by friction against a specific surface.
In summary, red phosphorus is the allotrope that does not catch fire easily, making it a safer form of phosphorus in certain applications. |
