Cellular respiration can be thought of as the opposite of photosynthesis. In cellular respiration oxygen is turned into carbon dioxide while in photosynthesis carbon dioxide is tuned to oxygen.
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Answer:
-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
Explanation:
Mass of nitrogen triiodide = 20.0 g
Moles of nitrogen triiodide = 

According to reaction, 2 moles of nitrogen triiodide gives 290.0 kilo Joules of heat on decomposition ,then 0.05063 moles of nitrogen triiodide will give :

-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
Psolution = X · PH_20
= 0.966 · 31.8 torr
= 30.7 torr