With the principle quantum number being 2, the maximum number that can share this is 8. You can use the general formula 2n^2 to calculate this number (n=quantum level), or you can use the concept of quantum numbers (n, l, m, s) to justify this answer.
(i) The pH of HCl is between 0 and 2.
(ii) the presence of Carbon Dioxide turns lime water milky or sees a white precipitate form on the surface of the lime water. Lime water is CaOH and when it reacts with Carbon Dioxide it forms a white solid (precipitate) Calcium Carbonate.