4. in order to decide whether a property is chemical or physical, you must know whether a. chemical or physical changes occur when the property is measured b. the property is extensive or intensive c. the property is intrinsic or extrinsic d. the property involved energy or matter

The answer is the property involved energy or matter...D

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answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.