Okay so just add all of them up the fine the x and the y and d the times that by the size of yiurn four head
A. Chlorine is the most electronegative element out of the possible choices. Generally (though not 100% of the time) electronegativity increases as you go further left and up the periodic table.
1st find the pOH = 14 - 4.75 = 9.25
then do 10^-9.25 = 5.62x10^-10 OH- concentration