(i) The element Y is a non-metal as all the elements of group 16 are non-metals.
(ii) The number of valence electrons of the element = Group number - 10
= 16-10 = 6.
(iii) Valency of Y = 8- number of valence electrons
= 8 - 6 = 2.
(iv) The name of the element is oxygen as it is the first element in group 16.
(v) Sodium is a group 1 element with a valency of 1. The valency of Y is 2. Therefore, when two atoms of sodium (Na) combine with one atom of Y, the formula of the resulting ionic compound is Na2Y.