A) Water has two hydrogen atoms and one oxygen atom - Molecular composition.
Water is chemical compound with definite and constant composition with distinct chemical properties.
B) Gasoline catches fire - Flammability.
Gasoline isvolatile, flammable organic mixture.
C) High lead levels in a lake kill fiss - Toxicity.
For example, oil refineries and chemistry industry produce a lot of toxic chemical waste which is released into environment.
D) The burning of coal releases heat - Heat of combustion.
For example, coal power plants use coal to heat water into steam, that steam than move a steam turbine, which generate electricity.
