To answer the question, we need to understand the factors that influence the explosiveness of coal dust. Here is a detailed analysis:
1. Temperature: While temperature can affect chemical reactions, it doesn't directly explain why coal dust would be more explosive in an enclosed space compared to an open space.
2. Surface Area: The surface area might play a role in the reaction rate, but it doesn't vary significantly between enclosed and open spaces to account for the difference in explosiveness.
3. Concentration: This is the amount of coal dust particles in a given volume of air. In an enclosed space, the concentration of coal dust is higher because the dust cannot disperse as it would outdoors. Higher concentration means more particles are close together, increasing the chances of a reaction and therefore, making it more explosive.
4. Volume: The volume of the space itself doesn't inherently affect the explosiveness of coal dust. An enclosed space with the same volume as an open space wouldn't necessarily be more explosive just based on volume alone.
5. Catalyst: The presence of a catalyst could affect the reaction, but it doesn't explain the difference between an enclosed and open space.
Given this analysis, the factor that best explains why coal dust is more explosive in an enclosed space compared to an open space is Concentration. Therefore, the correct answer is:
C. Concentration
