High Degrees of Symmetry in Molecules I recently encountered a question on a test:


  Substances whose molecules have a high degree of symmetry will have:
  
  
    A. a low specific heat
    B. a high melting point
    C. a high heat of fusion
    D. a low heat of vaporization
    E. strong Van der Waals forces
  


Looking through a few compounds, I found that $\ce{CO2}$ is symmetric (it's shape is a straight line), $\ce{CH4}$ is symmetric (tetrahedrons seem symmetric).
Through these examples, I was able to eliminate A, B, and C, and have a suspicious feeling about E, so I guessed D and was right. 

I was wondering what exactly "high degree of symmetry" meant. Through my math courses, I knew about rotational symmetry (where if you turn any 2-D shape in a plane by n degrees, it will look identical to the shape before the rotation).
Is a high degree of symmetry when the lowest possible value of n for a compound is over some constant, lets say 90 degrees, or is it something else?
I think that the question meant to test your knowledge about the polarity of simple molecules.

The fact that symmetric molecules contain identical bond polarities between the central atom and surrounding atoms, the net dipole moment usually tends to be zero, creating a nonpolar molecule. 

In other words, I think symmetry in this case refers to the fact that all of the surrounding atoms are identical.