Examples of Ionic Compounds

Q. $N{a}_{2}O$ has antifluorite structure. In $N{a}_{2}O,$ the coordination number of $N{a}^{+}\text{and}{O}^{2-}$ are, respectively:

Q. In a cubic lattice, atom X occupies the corners of the cube and atom Y occupies the end-centred positions and Z occupies the edge centres of the cube.

What will be the simplest formula of the unit cell if one of the face diagonals containing end centre atom is removed?

Q. $F{e}_3{O}_4$ has inverse spinel structure. What is not true about this solid?

1. $F{e}^{3+}$ ions are equally distributed between octahedral and tetrahedral voids
2. Tetrahedral voids are equally distributed between $F{e}^{2+}$ and $F{e}^{3+}$
3. Number of $O^{-2}$ >$F{e}^{3+}$ > $F{e}^{2+}$
4. Coordination number of $F{e}^{3+}$ = 8 throughout the unit cell

Q. By dissolving $13.6g$ of a substance in $20g$ of water, the freezing point decreased by ${3.7}^{\circ }C$. Calculate the molecular mass of the substance. (Molal depression constant for water = $1.863Kkgmo{l}^{-1}$)

1. $242.4g/mol$
2. $432.4g/mol$
3. $342.4g/mol$
4. $243.4g/mol$

Q.
A mineral has the formula $A{B}_2$ and crystallizes in the cubic close packed lattice, with atoms A occupying the lattice points. The co-ordination number and the fraction of tetrahedral sites occupied by atoms B are:

1. 4, 100%
2. 6, 75%
3. 1, 25%
4. 6, 50%

Q.

Which of the following statements is not true about NaCl structure

[DCE 2001]

1. Cl^- ions are in fcc arrangement

2. Na⁺ ions has coordination number 4

3. Cl^- ions has coordination number 6

4. Each unit cell contains 4 NaCl molecules

Q. A crystal of lead (II) sulphide has NaCl structure. In this crystal the shortest distance between a $P{b}^{2+}$ ion and $S^{2-}$
ion is 300 pm. What is the volume of a unit cell of lead sulphide ?

1. $216\times {10}^{-24}c{m}^3$
2. $2.7\times {10}^{-23}c{m}^3$
   
3. $216\times {10}^{-30}c{m}^3$
   
4. $27\times {10}^{-30}c{m}^3$

Q. What is the minimum distance between two $N{a}^{+}$ ions which are present along the edges in an ideal NaCl type crystal? Let, $r_{N{a}^{+}}$= radius of Na ⁺ and $r_{C{l}^{-}}$= radius of $C{l}^{-}$.

1. 
   $2\left(r_{N{a}^{+}}\right)$
2. $2\times (\sqrt{2}+1)r_{N{a}^{+}}$
3. $2r_{C{l}^{-}}$
4. $\sqrt{2}\times (r_{N{a}^{+}}+r_{C{l}^{-}})$

Q.
A mineral has the formula $A{B}_2$ and crystallizes in the cubic close packed lattice, with atoms A occupying the lattice points. The co-ordination number and the fraction of tetrahedral sites occupied by atoms B are:

1. 4, 100%
2. 6, 75%
3. 1, 25%
4. 6, 50%

Q.

Which of the following is TRUE for NaCl type structure?

1. Cations are present at tetrahedral voids

2. It has 8:4 coordination.

3. Cations are present at octahedral voids

4. It has 6:6 coordination

Q.

In a normal spinel type structure, the oxide ions are arranged in ccp whereas $\frac{1}{8}$ tetrahedral holes are occupied by $Z{n}^{2+}$ ions and 50% of octahedral holes are occupied by $F{e}^{3+}$ ions. The formula of the compound is ?

1. $Z{n}_{2}F{e}_2{O}_4$

2. $ZnF{e}_2{O}_3$

3. $Z{n}_{2}F{e}_2{O}_4$

4. $Z{n}_{2}F{e}_2{O}_2$

Q.

NaCI is an example of

1. Covalent solid

2. Ionic solid

3. Molecular solid

4. Metallic solid

Q.

In fluorite structure (CaF₂)

1. Ca²⁺ ions are ccp and F^- ions are present in all the tetrahedral voids

2. Ca²⁺ ions are ccp and F^- ions are present in all the octahedral voids

3. Ca²⁺ ions are ccp and F^- ions are present in all the octahedral voids & half of thetetrahedral voids

4. None

Q.

Which of the following is TRUE for Flourite type structure?

1. Cations are present at tetrahedral voids

2. It has 8:4 coordination.

3. Anions are present at octahedral voids

4. It has 4:8 coordination

Q. The number of equidistant oppositely charged ions in a sodium chloride crystal is

[MP PET 2001]

1. 8

2. 6

3. 4

4. 2

Q.

In calcium fluoride, having the fluorite structure the coordination numbers for the calcium ion $C{a}^{2+}$ and fluoride ion $\left(F^{-}\right)$ are

1. 4 and 2

2. 6 and 6

3. 8 and 4

4. 4 and 8

Q. $KCl$ has a rock salt lattice with edge length $=628pm$. Pick the incorrect option(s).

1. Second nearest neighbours of $K^{+}$ are 12, their sign is positive, with a distance of 444 pm
2. Second nearest neighbours of $K^{+}$ are 12, their sign is negative, with a distance of 364 pm
3. In an unit cell, number of effective KCl molecules are 6
4. Third nearest neighbours of $K^{+}$ are 8, their sign is negative, with a distance of 544 pm

Q.

In a solid AB having the NaCl structure, A atom occupies the corners of the cubic unit cell. If all the face-centred atoms along one of the axes are removed, then the resultant stoichiometry of the solid is:

1. $A{B}_2$

2. $A_{2}B$

3. $A_4{B}_3$

4. $A_3{B}_4$

Q. In a solid AB having the NaCl structure, A atom occupies the cornerns of the cubic unit cell. If all the face-centred atoms along one of the axes are removed, then the resultant stoichiometry of the solid is

1. $A{B}_2$
2. $A_{2}B$
3. $A_4{B}_3$
4. $A_3{B}_4$