Van't Hoff factor

A molecule M associates in a given solvent according to the equation M hArr (M)_(n) . For a certain concentration of M, the van't Hoff factor was found to be 0.9 and the fraction of asscoiated molecules was 0.2 . The value of n is:

If alpha is the degree of dissociation of Na_(2)SO_(4) the van't Hoff's factor (i) used for calculating the molecular mass is

If in solvent, n simple molecules of solute combine to form an associated molecule X is degree of association the Van't Hoff's factor 'I' is equal to:

One mole of a solute A is dissolved in a given volume of a solvent. The association of the solute take place as follows: nArarrA_(n) If a is the degree of association of A, then van't hoff factor i is expressed as:

What is Van’t Hoff’s factor?