Element X and Y have valence shell electron configuration as X: \[n{s^2}n{p^5}\] and Y: $n{s^1}$. Which compound is likely to be formed from $X$ and $Y$
A.${X_3}{Y_5}$
B.${Y_3}{X_5}$
C.$XY$
D.$YX$

Hint:To answer this question, you should recall the concept of formation of compounds. Ionic solids are held together by the electrostatic attraction between the positive and negative ions. The valencies of the ions are cross multiplied.

Complete step by step solution:
\[X:n{s^2}n{p^5}\] This electronegative element has a total 7 valence electrons, so it will have a tendency to accept one electron and complete its octet. So, its valency \[ = - 1.\]
 Y: electropositive alkali metal has one valence electron, so it has a tendency to lose one electron and complete its octet. Therefore, its valency \[ = + 1.\]
The reaction can be represented as:
\[Y \to {Y^ + } + {e^ - }\]and \[X + {e^ - } \to {X^ - }\].
This means that \[{Y^ + },{X^ - }\]have inert gas configuration. The compound is \[{Y^ + }{X^ - }.\]

Therefore, the correct answer to this question is option D.

Note:
You should know about the Ionic Compound Properties
1. Physical properties of ionic compounds: Due to the presence of the strong force of attraction between the positive and negative ions, ionic compounds are solids and are hard to break. They generally break into pieces when pressure is applied, hence they are considered brittle.
2. Melting and boiling points of ionic compounds: Due to the presence of electrostatic forces of attraction between ions, a large amount of energy is required to break the ionic bonds between the atoms. Thus, ionic compounds have high melting and boiling points.
3. The solubility of ionic compounds: Ionic compounds are generally soluble in polar solvents such as water whereas solubility tends to decrease in non-polar solvents such as petrol, gasoline, etc.
4. Conduction of Electricity: Ionic compounds do not conduct electricity in the solid-state but are good conductors in a molten state.