Minerals in geodes form spectacular euhedral crystals because . A. all of the elements incorporated in the crystals are in plentiful supply B. the crystals have abundant room to grow in their hollow surroundings C. minerals within geodes are always framework silicates D. minerals within geodes always contain iron

C. minerals within geodes are always framework silicates

Explanation:

This is true going by the facts that, it is only the silicates that can be able to form crystals as obtainable in diamonds etc. Since the minerals in geodes are in the framework of silicates families, they can be able to form euhedral crystals.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-