Element Electronic configuration X‌[Ne]3s23p1 Y‌[Ne]3s23p5 Z‌[Ne]3s2 According to given electronic configuration, X is Al,Y is Cl and Z is Mg. Along a period, the basic nature of oxides decreases and acidic nature of oxides increases. Mg, Al and Cl belong to same period with Mg on left side of the period, Cl on th right side and Al in between them. ∴ Oxide of Cl is i.e. Y will be most acidic oxide of Mg, i.e. Z will be basic and oxide of Al, i.e. X in between the other two. ∴ Correct increasing order acidic nature will be Z<X<Y