C protons and neutrons, electrons surround the nucleus of an atom in outer shells
Answer: E = - 19.611×
J
Explanation: The lowest possible energy can be calculated using the formula:

where:
Z is atomic number of the atom;
k is a constant which contains other constants and is 2.179×
J
n is a layer;
For the lowest possible, n=1.
Atom of Lithium has atomic number of Z=3
Substituing:

J
<u>The energy for the electron in the </u>
<u> ion is - 19.611 joules</u>
Sodium sulfate, Na₂SO₄, is a strong electrolyte. It means that it dissociates into 2 Na⁺ ions and 1 SO₄⁻ ion when dissolved in water. So, for every 1 mole of Na₂SO₄, there is an equivalent amount of 2 mol Na⁺ ions. The solution is as follows:
Moles of Na⁺ = (1.27 mol Na₂SO₄/L)*(1 L/1000 mL)*(343 mL)*(2 mol Na⁺/1 mol Na₂SO₄)
<em>Moles of Na⁺ = 0.87 mol</em>
Extensive property (like volume and mass), can be measured.