Answer:
Combustible substance
Combustion is a high-temperature exothermic redox chemical reaction that occurs between a fuel and an oxidant. Typically, this oxidant is oxygen from the air.
A combustible substance is one that burns in the presence of air and creates heat and light. Diesel, petrol, and kerosene, for example.
Non-combustible substance
Non-combustible compounds are those that do not burn in the presence of air. Glass and stones, for example.
Below is an explanation of the differences between combustible and non-combustible chemicals.