Question

What is denser kerosene, fuel oil, or butane

Answer 1

It depends on the temperature and pressure.

Under the same conditions, kerosene has a higher density.

we know that because we can google it, but a good rule of thumb is that the longer carbon chain has more density.

Answer 2

I'm not sure what type of fuel you're talking about. If you mean fossil fuel then kerosene has the highest density of all of the things you listed.