8. What are two pieces of evidence that molecules are always moving?

Explanation:

Sometimes this motion is easy to observe, such as when you see evidence of molecules in air bouncing dust particles around. Umm...for example, when you place a drop of food coloring into water, the motion of the water molecules eventually causes the food coloring to spread throughout the water.

  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-