2.0 g of h2 gas reacts with 32 g of o2 gas to form water. assuming the reaction goes to completion, how many grams of water will be produced?

In order to solve this problem, the balanced chemical equation of the reaction must be used. This gives the equation:

2H2 + O2 --> 2H2O

Next, the moles of the reactants must be used in order to apply their stoichiometric relationships. Note that 1 mole of oxygen needs 2 moles of hydrogen for the reaction proceed. Since there is only 1 mole of H2, only 0.5 moles of oxygen are consumed.

moles H2 = 2 g/ 2g/mol = 1 mole H2
moles O2 = 32 g/ 32g/mol = 1 mole O2

        2H2 + O2 --> 2H2O
i          1       1           0
c         1      0.5         1
e         0      0.5        1
 
 Assuming the reaction will proceed, there will be an excess of 0.5 mol O2 and a product of 1 mol H2O. This gives 18 grams of water. 

The answer is b because c don't explain why the moths are on them and it isn't a because as we know only one species of moth does this

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.