P, Q, R and S are four organic compounds. P is an unsaturated hydrocarbon.
Q burns but otherwise is unreactive.
R contains a C–C single bond and a C=C double bond.
S undergoes addition polymerization.
Which compounds are alkenes?
A. P and R only B. P, R and S C. P, Q and S D. Q, R and S

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a

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.