Final answer:
Ca, Se, and Kr are diamagnetic, while Mn and Co are paramagnetic.
Step-by-step explanation:
Paramagnetic atoms are those with unpaired electrons, which are attracted to a magnetic field. To determine which of the given elements are paramagnetic, we need to determine the number of unpaired electrons in their electron configurations.
Ca: The electron configuration of Ca is [Ar]4s². All the electrons in the 4s subshell are paired, so Ca is diamagnetic.
Mn: The electron configuration of Mn is [Ar]4s²3d⁵. There are five unpaired electrons in the 3d subshell, so Mn is paramagnetic.
Co: The electron configuration of Co is [Ar]4s²3d⁷. There are three unpaired electrons in the 3d subshell, so Co is paramagnetic.
Se: The electron configuration of Se is [Ar]4s²3d¹⁰4p⁴. All the electrons in the 4s, 3d, and 4p subshells are paired, so Se is diamagnetic.
Kr: The electron configuration of Kr is [Kr]5s²4d¹⁰5p⁶. All the electrons in the 5s, 4d, and 5p subshells are paired, so Kr is diamagnetic.