Final answer:
The solution that is hypotonic to red blood cells which normally contain 2.0% salt is a 1.0% salt solution because it has a lower concentration of salt, allowing water to enter the cells and potentially cause them to swell.
Step-by-step explanation:
A human red blood cell normally contains 2.0% salt. A hypotonic solution to red blood cells is one that has a lower salt concentration than the cells themselves, causing water to rush into the cells, potentially causing them to swell and rupture. Given the options, the solution that is hypotonic to red blood cells with 2.0% salt would be the 1.0% salt solution, as it has a lower concentration of salt compared to the red blood cells. So, the correct answer to the question is (b) 1.0%.
It is important to understand that a 1.0% salt solution is hypotonic compared to the normal 2.0% salt concentration inside red blood cells, according to osmosis principles where solvent moves from less concentrated (hypotonic) to more concentrated (hypertonic) solutions to reach an isotonic state, where the concentrations are equal.