a$)$ Consider the flow of air and water in pipes of the same diameter, at the same temperature, and at the same mean velocity. Which flow is more likely to be turbulent? Why?

b$)$ How does the log mean temperature difference for a heat exchanger differ from the arithmetic mean temperature difference $($AMTD$)?$ For specified inlet and outlet temperatures, which one of these two quantities is larger?

c$)$ What is the criteria of choosing the following mass transfer operations: distillation and extraction? Discuss each case separately.

d$)$ Compare and contrast absorption and stripping.