Which process occurs when heat alone causes material to break down without oxidation?

Which process occurs when heat alone causes material to break down without oxidation?

• A. Pyrophoric Material
• B. Recalling Observations
• C. Refueling
• D. Pyrolysis

Answer: (D)

Thermal decomposition without oxygen is called pyrolysis. When heat is applied to a material in the absence of air, the chemical bonds break and the substance breaks down into smaller molecules, gases, liquids, or a solid char, but no oxidation or flame occurs because there’s no oxygen to support combustion. This key distinction—breakdown driven purely by heat, without burning—is what separates pyrolysis from combustion. The other terms describe unrelated phenomena: a pyrophoric material ignites spontaneously in air due to oxidation; recalling observations and refueling are not processes of material decomposition caused by heat in the absence of oxygen.

Thermal decomposition without oxygen is called pyrolysis. When heat is applied to a material in the absence of air, the chemical bonds break and the substance breaks down into smaller molecules, gases, liquids, or a solid char, but no oxidation or flame occurs because there’s no oxygen to support combustion. This key distinction—breakdown driven purely by heat, without burning—is what separates pyrolysis from combustion. The other terms describe unrelated phenomena: a pyrophoric material ignites spontaneously in air due to oxidation; recalling observations and refueling are not processes of material decomposition caused by heat in the absence of oxygen.