Which of the following describes (auto) ignition temperature?

The term "auto ignition temperature" refers specifically to the lowest temperature at which a gas or vapor will ignite without the need for an external ignition source, such as a spark or flame. This means that when the temperature of the gas or vapor reaches this threshold, it can spontaneously ignite due to thermal energy alone.

Understanding this concept is crucial for safety operations aboard tankers and in various industrial applications, as it helps in assessing the risks associated with different fuels and vapors in the environment. Knowing the auto ignition temperature allows for proper handling and storage of materials to prevent accidental ignition and ensure safe operations.

The other descriptions do not accurately define auto ignition temperature. For instance, one of the options discusses the explosion of a mixture at a specific concentration, which relates to a different concept called the explosion limit or flammability limit. Another option mentions the production of explosive vapors, which again does not align with the specific definition of auto ignition temperature. Therefore, option D is the only choice that encapsulates the correct definition of auto ignition temperature.