A flask is weighed and has a mass of 50.0 grams. Then, 2.0 grams of sodium metal is added to the flask. Chlorine gas is pumped into the flask. This allows the sodium metal to react completely with chlorine to produce sodium chloride. The flask and sodium chloride are weighed and have a mass of 55.0 grams. What is the mass of the sodium chloride produced?

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

i'm pretty sure its b i might be wrong though!

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".