Which of the following techniques can be used for confirming the structure of a compound?

Nuclear magnetic resonance (NMR) is a powerful analytical technique used to determine the structure of organic compounds. It provides detailed information about the electronic environment of specific hydrogen or carbon atoms within a molecule. By analyzing the NMR spectrum, chemists can gather data about the number of hydrogen and carbon atoms, their connectivity, and the presence of functional groups. This helps in confirming the structure of a compound by allowing chemists to deduce how different atoms are arranged in space.

In contrast, the other techniques listed do not provide the same depth of information necessary for structural confirmation. Cold storage is typically used for preserving samples and does not contain analytical capabilities. The evaporation method is primarily a technique for concentration or purification and does not provide insights into molecular structure. Visual inspection can aid in identifying physical characteristics (such as color or state) but lacks the analytical precision required for confirming chemical structure. Therefore, NMR stands out as the definitive technique for structural confirmation in organic chemistry.