I read in several websites that triple bonds cannot rotate freely. However, I've also read in the book "Chemical Principles" the following lines: "Various types of evidence suggest that the electron density around the two C-O bonds in CO2 is actually cylindrically symmetric—that is, the electron density is homogeneous all around the O-C-O molecular axis." That intrigues me. Now I don't see any problems preventing the two C-O bonds to rotate like single bonds. Additionally, since the way CO2 bonds is quite similar to triple bond, will triple bond be cylindrically symmetric too? Can triple bond rotate like single bond? Btw, how can people know whether linear configurations like triple bond or CO2 can rotate around the bond? Thanks very much.