Answer the questions below: 1.Give an example of something that has matter.
2.Give an example of something that doesn't have matter.
3.What is the difference between an chemical change and a physical change?
4.What 2 main kind of changes can you observe involve chemical reactions?
5.What is a precipitate?
6.What is the difference between an endothermic reaction and an exothermic reaction?

i think it is true since you can test the answer and can use observations to complete it.

  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-

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter  

answerlinnaeus;