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Lithium:
Atomic number = 3. So, the electronic configuration = 2, 1. So, 1 electron is present in the outermost shell.
Carbon:
Atomic number = 6. So, the electronic configuration = 2, 4. So, 4 electrons are present in the outermost shell.
Oxygen:
Atomic number = 8. So, the electronic configuration = 2, 6. So, 6 electrons are present in the outermost shell.
Sodium:
Atomic number = 11. So, the electronic configuration = 2, 8, 1. So, 1 electron is present in the outermost shell.