Use the information below to answer the question that follows. Michael's soccer team has a game on a cold January day. One of the players on the other team hurts his leg. His
coach pulls out a small bag, makes some crushing motions, and the bag turn cold. The bag is placed on the injured
leg. In the meantime, the spectators are cold in the stands. To warm their hands they pull out small packages, crush
them, and the bags turn warm.
In the above narrative, what is the example of an exothermic reaction?
the soccer game
the ice pack
spectator package
the ball

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

  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-