What does the half-life of a radioisotope represent? A. It represents the type of radiation that is being emitted by the radioactive material.

B. It represents the amount of energy produced by the isotope's radioactive decay.

C. It represents the time it takes for half of the material to decay to a daughter element.

D. It represents how long the radioactive material has been in existence in that form.​

gold is my favorite solid.

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.