单项选择题
A.1s22s22p63s23p63d64s2B.1s22s22p63s23p63d74s1C.1s22s22p63s23p63d8D.1s22s22p63s23p63d84s2
A.32B.18C.8D.2
A.钙(Ca)B.金(Au)C.镨(Pr)D.钯(Pd)