Hybridisation

All the other three involves hybridisation of the central atom.

Carbon (At. no. in excited state

hybrids atom orbital which from bond does not take part in hybridisation. Carbon has no lone pair so, according to VSEPR theory the hybrid orbitals stay as far away as possible. In this case, the bond angle being . hybrid molecules are tetrahedral with bond angle hybrid orbitals are triangular planar with bond angle .