Lonic bonds form...

Ions
Molecules
Subatomic particles
Atoms

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

well, i believe that the answer is 2. : 3

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this