You decide you want to make spaghetti for supper you first like a gas stove because you need to cook the meat when the meat is cooked you add sauce to it then you put a pot of water on the stove to get it boiling the next step is to put spaghetti noodles in the boil finally you drain the spaghetti noodles and add the sauce which of the following describes the chemical change happening

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.