Grams. It is a smaller unit.
I think it's Molality because the moles of solute over the kilograms of solvent is equal to the molality...
Yes, an OH group from ethanol can form a hydrogen bond to the ether O atom in the same way as it can do so with the single-bonded O atom in the ester.
The O atom in the carbonyl group of the ester can also form H-bonds with ethanol.
<span>the process or action by which one thing absorbs or is absorbed by another.</span>
16 is the mass of an atom of Oxygen