# How to find the plane of symmetry in biphenyls and substituted cyclohexanes?

I was going through my text book, (Solomon&Frhyle) I came across a couple of of examples which I didn't understand.

1.

How is the molecule symmetrical? Upon folding the molecule over its plane of symmetry the cooh group will be placed over fluorine.

2.

Similarly in this in structures 3,4,5,6 a chlorine atom out of the plane and below the plane coincide.

3. It's written that for biphenyls to be chiral a can be the same as a'. (Same for b and b') But If a a' and b b' are the same them won't a plane of symmetry lie in the middle perpendicular to the plane of molecule.

• Anything between $40^\circ$ and $60^\circ$ sounds reasonable to me. – Ivan Neretin Dec 26 '17 at 15:42