NAME ONE FUEL WHICH BURNS WITHOUT GIVING OFF WATER VAPOUR? AND WHY?

The fuel that burns without giving out water vapour is coke which is a pure form of carbon. It has high carbon content and low amount of hydrocarbon.

Normally water vapour is given off when there is presence of hydrogen in a given fuel and as coke have very low hydrogen content. Therefore water vapour is not given out .It simply burns with the evolution of carbon dioxide.

C + O₂ →  CO₂