What must be true for a substance to be able to dissolve in water?
the solute particles must have a strong attraction for the water particles.
the solute must be able to react with water at the given temperature.
there must be enough energy to break the chemical bonds in the water molecules.
the temperature must be high enough to cause the solute to melt.

In order for a solute to dissolve in a solvent, the attractive forces between solute particles and the solvent particles must be stronger than the attractive forces between solute-solute and solvent-solvent particles. This is important so that the solute will remain in solution.

more infor would

a lot

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.