Problem: When people are dehydrated, or when medical care requires mixing a drug in a liquid solution, a 'normal saline' solution is used. This is 0.9% sodium chloride, so 0.9 g NaCl / 100 mL water solution; converting grams to moles shows this is 154 mM sodium and 154 mM chloride. Relate this to the osmolarity of the solution you identified as isotonic.