Three aqueous solutions of NaCl are labelled as ‘A', ‘B’ and ‘C with concentrations 0.1 M, 0.01 M and 0.001 M, respectively. The value of van’t Hoff factor for these solutions will be in the order of :

1. i_A < i_B < i_C

2. i_A > i_B > i_C

3. i_A = i_B = i_C

4. i_A < i_B > i_C

If the relative decrease in vapour pressure is 0.4 for a solution containing 1 mol NaCl in 3 mol of ${\mathrm{H}}_2\mathrm{O}$, then percentage ionisation of NaCl will be -

1. 60%

2. 80%

3. 40%

4. 100%