An example of a scientific question that could be investigated

Let me try: an example of a scientific question that can be investigated with an experiments is "at what temperature does iron melt"? Questions in physics ans chemistry are easily tested with experiments. an example of a scientific question that cannot be (I think) investigated with an experiments is "how does neuron activaton lead to us having the perception of free will"? Questions connected to human mind on a more general lever are not as easily tested with experiments: they need models rather than this.