<prompt> Osmolarity of 4?2 solution of sodium bicarbonate is -500 osmolelitre1000 osmolelitre1500 osmolelitre2000 osmolelitre  <response>: Ans. is b i.e., 1000 osmoielitre o 4-2 solution of sodium bicarbonate contains 0?5 mmolmL or 500 mmolml.o This solution will have osmoloarity 1000 mOsmL as solution contains two active osmoles, i.e., 500 mOsmole of Na and 500 mOsmole of HCO3- .o One mole of osmotically active particles is called one osmole. In case of non-dissociated solutes, one gram molecular weight of any substance contain similar number of osmotically active molecules osmoles, thus a molar solution of glucose contains 1 osmole. On the other hand, in case of dissociated solutes, one gram molecular weight of any substance contain the number of osmotically active molecules osmoles equal to the number of dissociated molecules, e.g., a molar solution of NaCl contains 2 osmoles 1 mole of Na and 1 mole of Cl-. The osmolar concentration of a solution in osmoielitre is called osmolarity. When expressed in osmoieKg of solution is called osmolality. 