If it is incomplete or complete combustion. Normally the problems question with tell you.
EX:
"In the presence of plenty of oxygen" is complete combustion
"Not enough oxygen present" is incomplete combustion
I think the answer would be trenches but I’m sorry if I’m wrong
You could use a scale to measure the mass as well as a cup to hold the water. If you were comparing the two, you should also probably use a graduated cylinder to get the same amount of each type of water.
Hope this helped ^_^
