Which element has the electron configuration 1s^2?

The correct electron configuration for an element denotes how many electrons are present in its atomic structure and how they are distributed among various atomic orbitals. In the case of the configuration 1s^2, it specifies that there are two electrons occupying the 1s orbital.

The element that corresponds to this specific electron configuration is helium. Helium has a total of two electrons, which fill the 1s orbital. Understanding that the 1s orbital can hold a maximum of two electrons provides a clearer insight into helium's stability as a noble gas, characterized by a complete outer shell.

The other elements listed, such as oxygen, lithium, and beryllium, have different electron configurations. Oxygen has six electrons and would have a configuration of 1s^2 2s^2 2p^4. Lithium, with three electrons, would configure as 1s^2 2s^1, while beryllium, with four electrons, has a configuration of 1s^2 2s^2. Hence, only helium is accurately represented by the configuration 1s^2.