Answer:
the reaction which produce oxygen gas on earth is the photosynthesis
Step-by-step explanation:
reaction; 6co2+6h2o, in the presence of sunlight and chrolophyl it produces= c6h12o6 + 6o2
effect of overtime accumulation of o2: severe cases of oxy toxity can lead to cell damage and death in living things and also cause changes in lungs, which r potentially hrmful