Which of the following species has the greatest
number of electrons?
1. sc2−
2. cl1−
3. fe2+
4. co4+
5. v

Mn's atomic number is 25 so you have 25 protons and 25 electrons in a neutral atom. Since no charge is shown, the number of electrons is 25
Ni's atomic number is 28 so you have 28 protons and 28 electrons in a neutral atom. This one shows a +3 so there are 3 missing electrons, the number of electrons is 28 - 3 = 25
Cu's atomic number is 29 so you have 29 protons and 29 electrons in a neutral atom. This one shows a +2 so there are 2 missing electrons, the number of electrons is 29 - 2 = 27
Ti's atomic number is 22 so you have 22 protons and 22 electrons in a neutral atom. This one shows a -2 so there are 2 EXTRA electrons, the number of electrons is 22 + 2 = 24

Bis the answerhope it !