NMR spectroscopy and X-ray crystallography are widely used for determining the three-dimensional structure of organic compounds. NMR spectroscopy provides information about molecular structure through interactions of nuclear spins, while X-ray crystallography directly visualizes the molecular arrangement using crystal diffraction data
| Group I | Group II |
| P) NaCl | 1) Coordination bond |
| Q) $H_2$ | 2) Polar covalent bond |
| R) $Pd-P$ bond in $Pd(PPh_3)_4 | 3) Covalent bond |
| S) $C-Cl$ bond in $CH_3Cl $ | 4) Ionic bond |

