How does the work needed to lift an object and the gravitational potential energy of the object compare?
they are equal
the work is greater
the work is less.
the comparison depends on the height.

They are equal.

Remember that energy is conserved . . . energy can move around from one place to another, but the total amount of it never changes.

Whatever gravitational potential energy the object has after it's lifted is exactly the work (energy) that was needed to PUT it up there.

This is a very powerful fact that's always useful when you have to solve problems on work, potential energy, and kinetic energy.  

Always remember:  If an object gets more energy during the problem, that energy had to come from somewhere.

hi there!

your question asks at which segment does freezing occur.

since we're talking about water, the freezing point of water will be 32 degrees fahrenheit or below.

hope this ! ~