Why / how does hydrogen bonding help ice cubes float?

First, we must understand:

What is Hydrogen Bonding?

Hydrogen Bonding is the interaction between Hydrogen atoms, with their molecules, due to the fact that their (Hydrogen atoms and bonds) are weak that even the other types of bonds are stronger.

(The other bonds are: covalent and ionic bonds)

(Hydrogen bonds are weaker than the average bonds listed above)

If you are to take how and why hydrogen bonds effect/affect ice cubes, we would have to look at how ice cube are formed. If you know, ice cubes can be created due to low temperatures (cold temperatures) making water into a solid. When ice cubes form into a sold, the spacing of the molecules become further apart, creating the density of the overall ice cube lighter than it was allowing it (ice cubes) to float.

the answer to your question is slate

allowed for the prediction of the properties of missing elements.