The partial electron configuration of an atom with 11 electrons is shown. 1s22s22p6X Which of the following does X represent?

Atomic number of an atom is equal to number of electrons or protons present in system. In present case, the atomic number is 11. It implies there are 11 electrons associated with the system.

Further, electronic configuration represents distribution of electrons in atoms. Thus in present case electronic configuration of atom is 1s2 2s2 2p6 3s1.

Thus, X represents 3s1.