X is 1s2 2s2 2p6 3s1
Y is 1s2 2s2 2p4
a) Y can for anion because it can accept 2 electrons in its 2p orbital. The anion formed will have charge -2.
b) X can form cation as it can loose 1 electron from its outermost 3s orbital. The cation formed will have charge +1.
c) X belongs to 1 group, 3rd period (X is sodium, Z=11)
Y belongs to 16th group, 2nd peiod (Y is oxygen, Z=8)
d) The formula of compound will be X₂Y.