Preparation of oil gas or petrol gas from kerosene oil or petrol involves the principle of

why kerosene oil floats on water?

How is the fire produced by burning oil (or petrol) extinguished ?

A trader mixes 25% kerosene to his petrol and then he sells the whole mixture at the price of petrol. If the cost price of kerosene be 50% of the cost price of petrol/what is the net profit percentage?