I would be inclined to go with A, C and D
Actually Rb or Rubidium in zero state has the following
electron configuration:
<span>1s22s2</span><span>2p6</span><span>3s2</span><span>3p63d10</span><span>4s2</span><span>4p65s1</span>
However we can see that the ion has a 1 positive charge,
which means that it lacks 1 electron, therefore the answer from the choices is:
<span>d.
rb+: 1s22s22p63s23p64s23d104p6</span>
