An element with atomic number 17 is placed in the group 17 of the long form periodic table. Element with atomic number 9 is placed above and with atomic number 35 is placed below it. Element with atomic number 16 is placed left and with atomic number 18 is placed right to it. Which of the following statements are correct .
a) Valency of the element with atomic number 18 is zero.
b) Elements with same valency will have atomic number 16, 17 and 18.
c) Valency of elements with atomic number 9, 17 and 35 is one.
d) Element with atomic number 17 is more electronegative that element with atomic numbers 16 and 35