Which of the following corresponds to the electron configuration [Kr] 5s^2 4d^5?

The electron configuration [Kr] 5s^2 4d^5 is accurate for Technetium (Tc). To understand this, it is important to break down the components of the electron configuration.

The notation [Kr] stands for the electron configuration of Krypton, which has a complete electron shell (total of 36 electrons). Following this core, the configuration shows an additional two electrons in the 5s subshell and five electrons in the 4d subshell. When you add these electrons, the total comes to 43 (36 from Krypton plus 2 from 5s and 5 from 4d). This corresponds to the atomic number of Technetium, which is 43.

In electron configurations, the order of filling subshells follows the Aufbau principle, and knowing where each element falls can help in identifying them. The elements listed in the alternatives either have more or fewer electrons than Technetium when following their respective configurations, thus making them incorrect in this context.

Therefore, the configuration given points specifically and accurately to Technetium due to its atomic number and the specific arrangement of electrons in its orbitals.