Which of the following solutions is not isotonic to human cells?
A)150 mM NaCl
B)300 mM urea
C)100 mM MgCl₂
D)300 mOsm NaCl

Question

Quizplus · Accepted Answer

Isotonic solutions have the same concentration of solutes as the interior of human cells, which is around 300 mOsm. Options A, C, and D have a concentration of NaCl that can be converted to mOsm by multiplying by 2. Therefore, options A and D have a concentration of 300 mOsm, which makes them isotonic to human cells. On the other hand, option B has a concentration of urea, which is not an ion and does not contribute significantly to osmotic pressure. Therefore, option B is not isotonic to human cells.

Which of the Following Solutions Is Not Isotonic to Human