Ihave like ten minutes left to submit my homework in
a student knows that the sublimation point of carbon dioxide (co ) is -78.5°c. that is, at this temperature, solid carbon dioxide will change state directly from a solid to a gas. the student is asked to predict the temperature at which gaseous carbon dioxide will change directly from a gas to a solid. which prediction will be supported by experimental evidence?

he period during which a solid is not changing state; its temperature is increasing

  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-

the answer to this question is 3.