The number main-group elements'valance electrons can be determined on the periodic table

Valance electrons can be determined by Group on the periodic table

Explanation:Valence electrons are the electrons present in the outermost shell of an atom. We can determine the total number of valence electrons present in an atom by checking at its Group in which it is placed in the periodic table. For example, atoms in Groups 1 the number of valence electron is one and for group 2 the number of valence electrons is 2.The groups have number of valance electrons as follow:

Group 1 - 1 valence electron.

Group 2 - 2 valance electrons.

Group 13 - 3 valence electrons.

Group 14 - 4 valance electrons.

Group 15 - 5 valence electrons.

Group 16 - 6 valence electrons.

Group 17 - 7 valence electrons.

Group 18 - 8 valence electrons.

Result: No of valence electron can be determined by the group no. of the element.

It changes food into energy that the organism can use.

The answer is a) carbon-12