Compare rotational energy barrier for indicated bond.

Ordinarily the barrier to rotation about a carbon - carbon double bond is quite high but in compound P double bond between two rings was observed by NMR to have a rotational energy barrier of only about 20 cal/mol., showing that it has lot of single bond character. The reason for this is

Ordinarily the barrier to rotation about a carbon - carbon double bond is quite high but in compound P double bond between two rings was observed by NMR to have a rotational energy barrier of only about 20 cal/mol., showing that it has lot of single bond character. The reason for this is

Ordinarily the barrier to rotation about a carbon-carbon double bond is quite high but in compound P double bond between two rings was observed by NMR to have a rotational energy barrier of only about 20 cal/mol The reason for this is

Which of the following has the lowest barrier to rotation about the indicated bond ?

Which of the following has the lowest barrier to rotation about the indicated bond ?

Pick out the correct statements about the barrier of rotation about the indicated bond in the given compounds