The awnsers would be D for the first one and A for the second. Let me know if you want an explanation.
I think it's called a hypothesis
The correct answer is: A. How does changing the amount of water affect the growth of corn?
While options B, C & D are not impossible to test, option A is the only question that can be tested using quantitative methods, such as statistical analysis. The question in option A states: "How does changing the amount of water affect the growth of corn?". This question is easily testable using scientific investigation, because controlled or measured amounts of water can be added to corn, and the consequent growth rate of corn can be easily measured and recorded. However, the questions in options B, C & D cannot be precisely measured using quantitative tools, since they aim to measure qualitative (subjective) factors, such as: ethics, happiness and disappointment.

velocity is a vector so it has a magnitude and direction so the answer would be B
In photosynthesis, using light energy, plants convert CO2 and H2O into O2 and C6H12O6
CO2= carbon dioxide
H2O= water
O2= oxygen
C6H12O6= glucose