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Answer:Chemical reactions often involve changes in energy due to the breaking and formation of bonds. Reactions in which energy is released are exothermic reactions, while those that take in heat energy are endothermic. exothermicA description of a chemical reaction that releases heat energy to its surroundings.
Plum-pudding model is different from the model that came after it as the Plum pudding model did not encounter the concept of nucleus it simply says compares atom with a pudding in which electrons are spread around as rasins in a pudding while the model that came after that is Rutherford's model explain that the atom that having nucleus that serves as a center of the atom.
Density is the mass of a substance per unit volume. Volume is the amount of space an object occupies. Chemical properties- These are properties that can only be observed by changing the identity of the substance
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