Group the electronic configurations of neutral elements in sets according to those you would expect to show similar chemical properties.

a. 1s^22s^2 2p^3
b. 1s^2 2S^2p^6 3s^2 3p^3
c. 1s^2 2S^2 2p^5 3s^2 3p^5 3d^10 4s^2 4p^5
d. 1s^2 2s^2 2p^5 3s^2 3p^6

Set A Set B

  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 would be a