Ascientific idea becomes valid when it
tested
biased
permanent
complex

A scientific idea becomes valid when it is tested.

Explanation:

Every scientific discovery or inventions starts with the creation of idea or imagination related to the invention. Followed by the idea or the proposal for the scientific finding, the researchers should experimentally prove his proposal or assumptions. So it should be tested experimentally, to prove the validity of scientific idea. Unless and until the idea has been tested experimentally, those theoretical assumptions are of no use and it is termed to be disqualified. So the scientific idea will become valid only when it is tested and proved.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.