Three skateboarders take three different paths to the top of the half-pipe to start skateboarding at position 1. The skateboarders are all the same
height and weight. Which skateboarder will have the greatest amount of
gravitational potential energy?
A-The skateboarder who took the stairs.
B-The skateboarder who skateboarded up the half-pipe.
C-The skateboarder who walked up the half-pipe.
D-The gravitational potential energy is the same for all of the
skateboarders.

  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-