A 1% aqueous solution of a substance is isotonic with 3% solution of glucose. The molar mass of the substance is

• 60 g

• 120 g

• 180 g

• 360

For isotonic solution :
Concentration of glucose solution = Concentration of second solution of given substance
Weight of glucose (solution -1)/ Molecular weight of glucose = Weight of  substance(second- solution) / Molecular weight of given substance
Molecular weight of given substance = M
Weight of glucose (solution -1) = 3 g
Weight of substance( solution-2) = 1 g
Molecular weight of glucose = 180 g

Thus
3/180 = 1/ M
M = 180/3 = 60 g Answer