Ignition temperature of ordinary combustibles lies between

• A. 100 to 300 F
• B. 50 to 150 F
• C. 1000 to 1500 F
• D. 300 to 1000 F

Answer: (D)

Ignition temperature is the temperature at which ordinary combustibles will ignite on their own when heated, without a flame. For common materials like wood, paper, and textiles, that autoignition point is in the hundreds of degrees Fahrenheit, roughly between 300 and 1000 F. Temperatures in the low hundreds (such as 50–150 F or 100–300 F) are far too low for spontaneous ignition under normal conditions. Conversely, temperatures in the 1000–1500 F range are much higher than what these materials typically need to ignite. So the broad, realistic range for the ignition temperature of ordinary combustibles is about 300–1000 F.