Hint :Smoldering (slow combustion) is a low-temperature, flameless process of combustion that is maintained by the heat produced when oxygen directly attacks the surface of a condensed-phase hydrocarbon. It's a low-temperature, flameless method of combustion of a condensed fuel that poses safety and environmental risks while also allowing for novel technological applications, but the fundamentals are largely unknown.
Complete Step By Step Answer: Until ignition and combustion will occur, three things must be present in the proper proportions: heat, oxygen, and fuel. Slow combustion reactions are described as combustion reactions that occur slowly and produce a small amount of heat. Slow combustion can be seen in the rusting and digestion of food processes. Slow combustion is a form of combustion that takes a long time to complete. Slow combustion is illustrated by cellular respiration. Glucose is oxidised during respiration, releasing carbon dioxide and energy in the process. This is a reaction that is very close to combustion.
Note : Rust is an iron oxide, a typically reddish-brown oxide formed when iron and oxygen react catalytically in the presence of water or air moisture. Rust is made up of hydrous iron(III) oxides and iron(III) oxide-hydroxide, and it is commonly associated with refined iron corrosion.