1. how many valence electrons are in the element gallium? explain how you determined the number.
2. how do scientists identify the bond type (ionic or covalent) of a chemical formula?
3. how do scientists predict the polarity of molecules? be sure to mention both polar and nonpolar molecules.
4. this questions has three parts:
a. how do intermolecular forces differ from intramolecular forces in terms of strength?
b. describe each of the four types of intermolecular forces.
c. list the four types of intermolecular forces in order of increasing strength.

  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 is the most commonly accepted one