Answer: # 1: c. #2: d. #3: a
Step-by-step explanation:
#1 is C. because the equation for cellular respiration is C₆H₁₂O₆
+ 6O2 --> 6H20 + 6CO2 + ATP
This says the reactants (inputs) are oxygen and glucose and the products (outputs) are water, carbon dioxide, and ATP. 1 glucose molecule makes 6 carbon dioxide, so 3 glucose would make 18 carbon dioxide molecules.
#2 is D. because the law of conservation of matter states that matter cannot be created nor destroyed, so the weight before and after cellular respiration would stay the same, as the matter would not change.
#3 is A. because a model would show the exact way the molecules would be arranged, while a formula only tells you how many there are, not the way they would be made up.
Hope this helps :)