The more non-metallic element from the elements ‘X’ and ‘Y’ having electronic configuration 2, 8, 5 and 2, 8, 6 respectively.

‘Y’ with electronic configuration 2, 8, 6.

Reason

X will belong to group 15 and Y will belong to group 16 and as non-metallic increases across a period (i.e., from left to right) hence Y will be more non-metallic character than X.