Please help me with this

the answer is mixtures.

Explanation:

mixtures can be separated physically. elements like the ones on the periodic table cannot be further broken down. compounds are bonds between two or more elements and can only be broken down chemically.

A pure substance, any compound or element, can't be separated into different atoms by physical methods. A chemical reaction must occur to separate a compound into its different atoms/elements.

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.