Dalton's contribution was different from thatof the ancient Greek who postulated the existence of atoms. Point out the differences between the two ideas​

Democritus atomic theory is the ancient theory that describes the nature of matter in terms of atoms whereas Dalton atomic theory is a modern scientific theory that describes the nature of matter in terms of atoms. According to Dalton's theory, atoms are identically same, but Democritus had no idea about it. Atoms are never created nor destroyed, they just rearrange.

Explanation:

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.