A feed containing equimolar amounts of methanol and water is mixed with 10 moles of a 40 % mol aqueous methanol stream. The mixture enters a first separation unit that creates two streams. A top stream exits the separation unit that contains 70 % mol methanol and rest water. The bottom stream, which is 70 moles enters a second separation unit. A top stream exists the second separation unit as a 50 % methanol & 50 % water mixture. The other stream is unknown. If the fresh feed to the system is 100 moles (equimolar mixture) and the two top streams exiting the separation units have the same flow, draw the flow sheet and find the molar flow and the composition of the bottom streams existing the second separation unit?

93.2 ml + 3920 ml = 4013 ml total  

(93.2 ml) * (2.03 m) / (4013 ml) = 0.0471 m

the volume in in l of the diluted solution would be 0.0471 m.

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.

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally