Glucose reacts with oxygen to produce carbon dioxide and water: C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l)
Just before a chemistry exam, suppose a friend reminds you that glucose is the major fuel used by the human brain. You therefore decide to eat a candy bar to make sure that your brain does not run out of energy during the exam (even though there is no direct evidence that consumption of candy bars improves performance on chemistry exams). 
You choose a candy bar : Kitkat 21g of glucose 

Showing all calculations, demonstrate how many grams of carbon dioxide you will produce and exhale into the exam room?​