Do all the non-trivial zeros of the Riemann zeta function have a real part of one-half?

There's a genuine prize of one million dollars to whoever solves it.

I see the moon at day all the time.

 1) You and Fayceless have the right idea but gravity isn't actually exerting a force (otherwise you could express gravity in newtons), it is more of a missunderstanding between what a straight line actually is within space-time.  We tend to view our world from a Euclidian Geometry viewpoint, which in most mundane matters on Earth is perfectly indistinguishable from non-Euclidian Geometry, but in reality the gravity isn't exerting a force so much as changing the definition of a straight line within the gravitational field by curving space (ie its more apt to call it a geodesic than a "straight" line).  In effect the definition of a straight line is bent/curved by gravity and the object travels the "straight line" as it has been redefined within the warped space.

This picture may be odd but these are all examples of straight lines in their respective types of geometry. Note that in each case the two "parallel" lines have a perpendicular line between them which meets them at a right angle as it is defined within the respective geometries (also note this is a 2d representation of something that actually occurs in 3d, so its not exact):

As I said it can be a bit odd to wrap your head around it. 

2) The best way to describe this is that the Earth wants to fly off into space and the sun is "bending" the definition of a straight line such that the "straight line" of flying off into space actually curves by the sun.

3) Don't really have anything to add to what you said here.

PS - I know this was probably a bit of nit-picking, so please don't take it the wrong way. Just something I don't think very many people know about.

3) Why is the water atom polar?
oxygen has a higher electronegativity then hydrogen. Since the the oxygens are not on opposite sides of the hydrogen, the side with the two oxygens has higher electronegativity, while the side without the oxygens has lower electronegativity. This creates a dipole, hence water is polar

4) What is the difference between ionic and covalent bonding?
Ionic bonding is when one element gives its electron to another element. The loss and gain of an electron by either element causes one element to become postively charged and the other negatively. Thus they stick together. For example, sodium needs to give away one electron to have a full outer shell (which is ideal) and Chorine needs to gain one electron to have a full outer shell, so the Sodium gives its electron to chlorine
Covalent bonding is when both elements need to gain electrons (as opposed to losing them) to achieve a ful outer shell. To achieve this, the elements 'share' electrons. For example Oxygen, which needs 2 electrons to fill its outer shell, shares two electrons with another Oxygen atom, so both essentially have a full other shell.

I agree it's not a force, but it is valid to view it as an interaction involving gravitons and field theory. Any unified, fundamental (quantum-mechanical, probably string theory) solution would have it as that rather than the relativity explanation (which is valid at larger scales).

If you are going by field theory, weight is the force that a gravitational field produces. If you go by relativity, as you say, the force is a psuedoforce [i.e. not real] based on our frame of reference [much like centrifugal force].