Except for that they can't, because everyone who believes in science just says that the reason they believe that science will be able to explain everything is that it has explained everything so far. This is just begging the question, and it's clear that no matter how much evidence there is that there are some things that science can't explain these will just be written off by those who have 'faith' in science. You can go over to r/science or r/atheism and find literally thousands of examples of this.
>What reasons? Be precise enough and you get a Nobel Prize and eternal adulation.
The obvious one would be that there is absolutely nothing to suggest that consciousness is material in nature. But again, the true believers refute this by listing all the other things that we didn't understand until science came up with some explanation, and saying that therefor science will most likely also be able to explain consciousness one day.