About which of the following can you ask scientific questions

Scientific questions are question which are solved involving experiments, observations, or surveys.

Like, Is cancer caused by uncontrolled cell division.

Scientific questions are always testable questions. They can be solved by using scientific techniques like PCR, titration etc.

Here the given question in the example can be tested, by making the observations of the cell division of the cancer patients. Then by inducing uncontrolled cell division into normal cells to look for the effect of cell division on cancer.

The questions like, "is sadness can be controlled by talking?" is not a scientific question.

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.