You Are Given Two Identical Vials of What You Are

Multiple Choice

You are given two identical vials of what you are told are identical molecules.However,one vial weighs more than the other,albeit on a very minute scale.One sample weighs more per molecule because the component elements have

A) different isotopes.
B) an integer atomic mass value.
C) more than one atomic number.
D) various means of forming chemical bonds.
E) different isomers.