Question

Why H2SO4 is not preferred during the reaxn of alcohol with ki

Answer 1

In the presence of sulphuric acid (H2SO4), KI produces HI

2KI + H2SO4 → 2KHSO4 + 2HI

Since H2SO4 is an oxidizing agent, it oxidizes HI

2HI + H2SO4 → I2 + SO2 + H2O

As a result, the reaction between alcohol and HI to produce alkyl iodide cannot occur. 

that's all...hope you understand