<span>An element is a pure substance that cannot be broken down into anything simpler by physical or chemical means.</span>
The reason they have to be so accurate and precise is because, let's say you were doing a lab or something that was involving chemicals. If you had to put a certain amount of chemicals in your experiment, but when you were doing to the math, you messed up and didn't go back and even bother to fix it, that is a really BIG issue. Because something will probably happen to your chemicals because you might have added to much of something into it. So that's why you always have to be so precise and accurate!
Because these volcanic activities happen on plate tectonics.
This is not the best answer but I hope it could help you.
