What makes a question scientific is that we are able to test our hypothesis.
For example: Will increased sunlight cause more seeds to grow. We can test that simply by placing seeds in the sun and some out of the sun.
If you cannot test an hypothesis, then it is NOT scientific
For example: Macroevolution isn't a scientific question because we cannot test whether or not complex organisms come from simpler organisms. It can only be classified as an Hypothesis at best.