Up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record, about 80 million years ago. but in 1938, a live coelacanth was discovered off the coast of south africa that was compared to the fossil record and found to be the same species what goal of science does this discovery represent

Scientific Ideas are always open to revision. Because when an Hypothesis is developed we use the knowledge we possess to do it. However our knowledge can be limited.

Explanation:

The basic idea of proposing an hypothesis is that we gather all the information we can to explain the closest claim on reality. The thing is that we are sensorial beings and we interpret reality with what we perceive, that is why we can be wrong even though if we are positivist scientists. We try to explain reality as much as we can an because we do it since a human being point of view we can be wrong because we don't possess the best sensorial receptors. That's why we have to be very academic and strict, because we need to build our ideas as strong as we can so they can't be falsed that easily.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.