Spontaneous combustion occurs itself with external heat....no external heat is required for it's burning...so the correct answer is B.

Spontaneous Combustion: No External Heat Required

Spontaneous combustion is a process in which a substance ignites and burns without the need for an external ignition source, such as a flame or spark. This phenomenon occurs when a material undergoes self-heating and reaches its ignition temperature, resulting in a fire. The correct answer to the given question is option B, spontaneous combustion.

Explanation:

Spontaneous combustion can occur in various materials, including certain organic compounds, such as oily rags, coal, hay, and even some chemical substances. It happens when these materials undergo a slow oxidation process, producing heat as a byproduct. The heat generated within the material gradually increases, eventually reaching a point where it becomes self-sustaining and leads to ignition.

Factors Influencing Spontaneous Combustion:

Several factors contribute to the occurrence of spontaneous combustion. These include:

1. Porous Structure: Materials with a porous structure, such as coal or hay, provide ample oxygen supply for the oxidation process to occur.

2. Moisture Content: Moisture content plays a crucial role in spontaneous combustion. If a material contains excessive moisture, it can hinder the oxidation process, preventing self-heating and combustion.

3. Heat Insulation: Insulation traps the heat generated within the material, increasing its temperature and promoting self-heating.

4. Presence of Flammable Substances: The presence of flammable substances within a material can increase its susceptibility to spontaneous combustion. For example, oil-soaked rags contain flammable oils that can easily ignite when exposed to heat.

Prevention of Spontaneous Combustion:

To prevent spontaneous combustion, it is important to take certain precautions:

1. Proper Storage: Store materials prone to spontaneous combustion in well-ventilated areas, away from other flammable substances.

2. Moisture Control: Maintain appropriate moisture levels in materials to prevent self-heating and oxidation.

3. Safe Disposal: Dispose of oily rags or other flammable materials properly, ensuring they are stored separately in fire-resistant containers.

4. Regular Inspections: Regularly inspect areas where spontaneous combustion is likely to occur to detect any signs of self-heating or high temperatures.

Conclusion:

Spontaneous combustion is a fascinating phenomenon where a material can ignite and burn without the need for an external heat source. Understanding the factors that contribute to spontaneous combustion and taking necessary precautions can help prevent accidents and ensure safety in various industries and everyday life.