Final answer:
Flares containing highly flammable materials, such as hydrogen gas, or those designed as fuel/oxidant mixtures, will ignite when exposed to oxygen due to the increased reaction rates facilitated by the gas.
Step-by-step explanation:
The type of flare that will ignite if exposed to oxygen is one involving flammable gases such as hydrogen. Hydrogen gas is highly flammable and produces a significant amount of heat when it reacts with oxygen. This reaction is demonstrated by the equation 2H₂(g) + O₂(g) → 2H₂O(l) +572kJ. Hydrogen forms explosive mixtures with air within a concentration range of 4-74% and with chlorine at 5-95%. The addition of a greater concentration of oxygen can cause a combustible mixture to ignite, which is highlighted by the fact that oxygen is the only gas that supports combustion. Additionally, we have the example of a glowing splint which, when inserted into pure oxygen gas, will burst into full flame due to the increased reaction rate resulting from the higher oxygen concentration.
Flares used in various industries and emergency situations can contain both liquid fuel/oxidant mixtures and solid mixtures that react with oxygen. Those with liquid fuel/oxidant mixtures might have a characteristic green flame, while flares with solid mixtures can produce a more powerful yellow flame when ignited. Meanwhile, in astrophysics, solar flares that release a tremendous amount of energy are typically associated with magnetic fields' interactions, though this concept diverges from the context of chemical reactions between flammable substances and oxygen.
In summary, the specific flare type that ignites when exposed to high concentrations of oxygen includes those containing combustible gases like hydrogen, as well as flares designed with mixtures used for liquid fuel or solid propulsion systems. Oxygen facilitates combustion reactions, making it a critical component for the ignition of flares.