Find the steady state molar flow rate of HCl, in mol/s, through the plastic wall of a spherical container at 25°C with an HCl solution inside and outside the container. The container has an outer diameter of 60 mm and a wall thickness of 20 mm. Assume the HCl concentration in the wall at r = 10 mm is maintained at 1.0 X 10-5 M and the HCl concentration in the wall at r = 30 mm is maintained at 1.0 X 10-6 M. The ionic diffusion coefficients in the membrane at 25°C are 9.31 X 10-3 mm2/s for H+ and 2.03 X 10-3 mm2/s for Cl−. Assume there is no current in this problem.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

a is the correct answer

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.