Guar Identify if the following sentences are true or false. Write True if true or Fif False 1. When oxygen combines with another substance (as fuel) an object may produce fire with heat and light. 2. If oxygen is present in a wet material with iron, such as nail or steel bar, the formation of rust occurs. 3. The presence or absence of oxygen has various effects on matter. 4. The changes in color of the inner fleshly part of an eggplant is due to the exposure of water. 5. In combustion, oxygen, fuel and heat are always present.