What is the molarity of a potassium iodide solution prepared from 0.400 mol of ki in 125 ml of solution?

Answer is: molarity of a potassium iodide solution is 3.2 M.

n(KI) =0.400 mol; amount of substance for potassium iodide.
V(solution) = 125 mL ÷ 1000 mL/L.
V(solution) = 0.125 L; volume of solution.
c(KI) = n(KI) ÷ V(solution).
c(KI) = 0.4 mol ÷ 0.125 L.
c(KI) = 3.2 mol/L; concentration of potassium iodide solution.

It requires one electron to complete its octet.

Explanation:

Lewis-dot model shows the valence  electrons present in the atom by the help of dots.

Valency of an element is defined as the electrons gained or lost in order to attain stable electronic configuration.

Thus an atom with 7 valence electrons must be an element of group 17 or halogens and will all gain 1 electron to attain stable noble gas configuration or complete its octet.