Question

Is Biphenyl a planar?

Answer 1

The structure would be influenced by the hybridization and other factors which can affect the effects of hybridisation too.
According to the hybridisation of carbon connecting the phenyl groups i.e. $s{{p}^{2}}$ ; the structure should be planar.

Complete step-by-step answer: Let us study Biphenyl in detail;
Biphenyl is an aromatic hydrocarbon compound with molecular formula as ${{\left( {{C}_{6}}{{H}_{5}} \right)}_{2}}$ . It is an intermediate for the production of many other organic compounds as crop protection products and plastics. Mostly insoluble in water but soluble in many organic solvents.
The structure of the compound is as follows;

Though the structure represents the planar structure, it is not. This is because the hydrogen present in the compound at the ortho positions (of both the phenyl groups) does not allow the rotation about the central bond joining the two phenyl rings. This is completely due to steric hindrance.
Hence, there can be some deviation from the planar structure.

Therefore, Biphenyl is not planar.

Note: Biphenyl can also be called as diphenyl, phenyl benzene or limonene.
Along with the steric hindrance, the phenyl groups are atropisomers of each other i.e. the conformational isomers which can be isolated at high temperature. This is also a factor for its non-planar structure.