The producer gas made from the coke has the following composition :
co : 28%, co2 : 3.5%, o2 : 0.5% and n2 : 68%.
the gas burned with such a quantity of air that the oxygen from air is 20% in excess of the net oxygen required for complete combustion. if the combustion is 98% complete, calculate the weight of the gaseous product formed. given the oxidation reaction as below:
co + ½ o2 à co2

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.