Consider the following statements: 
1) IIlite is the mineral largely responsible for the swelling and shrinkage behavior of clayey soils. 
2) A differential free swell value of 55% indicates a soil with low degree of expansiveness. 
3) Higher the plasticity index of a soil, greater its swelling potential. 
4) A low shrinkage limit of a soil indicates possibility of swelling at low water content. 
Which of the above statements are correct?