vant haff factor

A solute dissociate in solution according to reaction 2Ato5B , If solute shows 30% dissociation then van't Haff factor will be:-

The vant Hoff factor (i) accounts for

For a solute undergoing association in a solvent, the van't hoff factor

In which of the following the vant Hoff factor (i) is equal to one:

Problem based on vapour pressure,van't hoff factor, boiling point