What happens to the mass of an object when it is consumed during combustion?

When an object is consumed during combustion, the mass decreases because the combustion process involves a chemical reaction where the material reacts with oxygen to produce gases and other byproducts. During this process, the original material transforms into different substances, primarily consisting of carbon dioxide, water vapor, and other combustion products.

Since these byproducts escape into the atmosphere as gases, the mass of the remaining material—the ash or unburned residue—is less than the original mass of the object before the combustion. This loss of mass is consistent with the principle of conservation of mass, which states that mass can neither be created nor destroyed in a chemical reaction, but in the case of combustion, some of the mass is converted into gaseous forms that can no longer be measured in the same physical form. This is why the correct answer emphasizes a decrease in mass.