Elements X and Y have valence shell electronic configurations $X=n{s}^{2}n{p}^5;Y=n{s}^{2}n{p}^3$. Which compound is likely formed from X and Y?

The correct option is D $Y{X}_3$
According to the octet rule, elements tend to form bonds with each other in such a way that each of the elements get 8 valence electrons. Here, X has 7 valence electrons and Y has 5 valence electrons. Covalent compounds are most likely to be formed where sharing of electrons takes place here. Each X atom shares one electron with Y, so Y is surrounded by three X atoms and we get $Y{X}_3$