Answer: reactive
Explanation: Noble gases are the elements of group 18. This series contains helium, neon, radon krypton and radon. The noble gases are the least reactive of any elements on the periodic table

The Energy required for photosynthesis is absorbed by plants through green pigments known as Chlorophyll, in the form of Sunlight which is later used up during photosynthesis to produce Glucose.

I believe the answer you're looking for is photosynthesis, where plants release oxygen and humans use this to release carbon dioxide to the plants.