Question

The osmolarity of blood is. 30osmol. When blood cells were placed in a solution the blood cells crenated. Which of the following is most likely to be the solution into which the blood cells were placed.
a) 0.15 m NaCl
b) 0.15 m glucose
c) 0.30 m NaCl
d) 0.30 m glucose

Answer 1

THE CORRECT OPTION IS C

Osmolarity means total number of solute particles per litre.

The crenation of blood cells means the contraction of blood cell when placed in a solution. This contractions is due to water loss through osmosis. It will take place when cell are placed in hypertonic solution because only then solvent will move towards hypertonic solution.

This means the solution should have greater osmolarity than 0.30.

a) it will dissociate into Na+ and Cl- to give 2×0.15= 0.30 osmolarity. Thus isotonic with blood cell.

b) 0.15 m hypotonic

c) 0.30 m NaCl will have 0.60 osmolarity because total number of ions is twice to the NaCl concentration. So, hypertonic .

d) again isotonic .

The correct option is c)