The van't hoff factor (i) is given by the expression:

(a) i= Normal molar mass  abnormal molar mass

(b) i= Abnormal molar mass  normal molar mass

(c) i= Observed colligative property  calculated colligative property

(d) i= Calculated colligative property  observed colligative property

The correct choice among the given options is:

1. a and b

2. b and c

3. c and d

4. a and c

Hint: Van't Hoff factor (i)= normal molar mass  abnormal molar mass