You measure the bubbles because oxygen is produced during photosynthesis so therefore by measuring the bubbles if you increase the water level you would see the rats of photosynthesis increase
Answer: I believe the Answer is A
1) Reaction is exothermic because energy of products is less than energy of reactants
2) Energy is released because the reaction is exothermic
3) 350
4) 150
5) 500-350=150
6) 350-150=200