Answers

2015-11-15T22:14:52+05:30
Because at night trees take in o2 and take out co2 which human being is not in need to take
1 4 1
2015-11-15T22:16:38+05:30
Because at night tree do not perform photosynthesis but do respiration only thats why it releases CO2 and uses O2 and  in morning it releases more O2 compared to CO2. 
1 5 1