Question

An \[{\rm{A}}{{\rm{B}}_{\rm{2}}}\] type structure is found in:
A. \[{\rm{NaCl}}\]
B. \[{\rm{Ca}}{{\rm{F}}_{\rm{2}}}\]
C. \[{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}\]
D. \[{{\rm{N}}_{\rm{2}}}{\rm{O}}\]

Answer 1

Hint: An ionic solid defines the solid that is made of cations and anions. Some examples of ionic solids are sodium chloride, cesium chloride, etc. There are different types of ionic solids such as AB type, \[{\rm{A}}{{\rm{B}}_{\rm{2}}}\] type, \[{{\rm{A}}_{\rm{2}}}{{\rm{B}}_{\rm{3}}}\] type etc.

Complete Step by Step Answer:
Let’s understand the \[{\rm{A}}{{\rm{B}}_{\rm{2}}}\] type solid . In \[{\rm{A}}{{\rm{B}}_{\rm{2}}}\] solid type, coordination numbers of the anions and the cations are different. For example, in \[{\rm{Ca}}{{\rm{F}}_{\rm{2}}}\], \[{\rm{Ca}}{{\rm{F}}_{\rm{2}}} \to {\rm{C}}{{\rm{a}}^{2 + }} + 2{{\rm{F}}^ - }\]
In calcium fluoride, the cubic close-packed structure is formed by the calcium ions and the tetrahedral holes are occupied by the fluoride ions.

Now, we will understand the AB solid type. In this solid, the coordination numbers of the cations and anions are the same as in sodium chloride, etc. Therefore, AB type of solid breaks in the following way:
\[{\rm{AB}} \to {{\rm{A}}^ + } + {{\rm{B}}^ - }\]
Similarly, NaCl breaks into sodium and chloride ions.
\[{\rm{NaCl}} \to {\rm{N}}{{\rm{a}}^ + } + {\rm{C}}{{\rm{l}}^ - }\]
Therefore, A is not correct.

Let’s discuss option C. The dissociation of \[{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}}\]happens in the following way:
\[{\rm{A}}{{\rm{l}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}} \to 2{\rm{A}}{{\rm{l}}^{ + 3}} + 3{{\rm{O}}^{2 - }}\]
Therefore, this type of ionic solid is of the type \[{{\rm{A}}_{\rm{2}}}{{\rm{B}}_{\rm{3}}}\] . Therefore, option C is not right.

The option D is \[{{\rm{N}}_{\rm{2}}}{\rm{O}}\]. The dissociation of \[{{\rm{N}}_{\rm{2}}}{\rm{O}}\]is :
\[{{\rm{N}}_{\rm{2}}}{\rm{O}} \to 2{{\rm{N}}^ + } + {{\rm{O}}^{2 - }}\]
Therefore, this type of ionic solid is A, B type. Therefore, D is wrong.
Hence, option B is true.

Note: Some of the properties of ionic solids are that they are present in the form of crystals. They are bad conductors of electricity if they are present in a solid state. In the aqueous medium, they are good conductors of electricity because of the availability of free electrons.