VSEPR and molecular shape:

 

Carbon appears in molecules with a variety of shapes.  According to Valence Shell Electron Pair Repulsion (VSEPR) Theory, groups of valence electrons determine molecular shape by repelling each other.  The shape of a molecule is determined by the number of groups of electrons (the steric number) around the central atom.

Examples of groups:

 

Question:  How many groups of electrons are there around the carbon atom in the following methane molecule?

 

         

(a)    one

(b)   two

(c)   three

(d)   four