The element of the 3d series with the lowest enthalpy of atomisation is copper (Cu). Copper has a completely filled \( 3d^{10} \) configuration, which makes it highly stable. The stability of the \( 3d^{10} \) configuration reduces the energy required to break the metallic bonds during atomisation, hence lowering the enthalpy of atomisation. In contrast, elements like zinc (Zn) and manganese (Mn) have less stable electron configurations and require more energy to break the bonds during atomisation.
Thus, copper (Cu) has the lowest enthalpy of atomisation due to the stability provided by its filled \( 3d^{10} \) configuration.
A school is organizing a debate competition with participants as speakers and judges. $ S = \{S_1, S_2, S_3, S_4\} $ where $ S = \{S_1, S_2, S_3, S_4\} $ represents the set of speakers. The judges are represented by the set: $ J = \{J_1, J_2, J_3\} $ where $ J = \{J_1, J_2, J_3\} $ represents the set of judges. Each speaker can be assigned only one judge. Let $ R $ be a relation from set $ S $ to $ J $ defined as: $ R = \{(x, y) : \text{speaker } x \text{ is judged by judge } y, x \in S, y \in J\} $.