What can be expected when more oxygen is added to a combustion reaction?

When more oxygen is added to a combustion reaction, a color change and change of texture can be expected primarily due to the enhanced combustion process. Increased oxygen availability allows for a more complete combustion of the fuel, leading to a more vigorous reaction. This can produce higher flame temperatures, which might change the color of the flame and cause changes in the physical characteristics of the materials involved.

For instance, in the case of burning hydrocarbons, the flame may shift from a yellowish color (incomplete combustion producing soot) to a blue color (complete combustion) when there is plenty of oxygen. Additionally, materials around the combustion site can also undergo changes in texture, such as drying out or becoming charred as a result of increased heat and more efficient energy release from the combustion process.

The other options - no change in color or texture, a change in odor, and a decrease in heat output - do not accurately reflect the typical outcomes of increasing oxygen in a combustion reaction, as there generally will be observable changes in both flame characteristics and material properties.