Part 1
If water does not spill at the top point of the circular motion then for the minimum speed condition we can say normal force will be zero at the top position



given that
R = 1 m
g = 9.8 m/s^2
now from above equation we have

Part b)
for minimum value of angular speed we will have



This is hard sorry but I need to anwser
Are you referring to the fact that water is a compound while hydrogen is an element? If I'm wrong just comment and clarify and I can edit it, I don't even know what kind of unit you're in. :)