Ionic Compounds and Radius Ratios

Q. Given: Radius of $A^{2+}$ = 100 pm; Radius of $C^{+}$ = 240 pm; Radius of $B^{2-}$ = 300 pm; Radius of $D^{-}$ = 480 pm. Which is/are correct statement?

1. The coordination number of $A^{2+}$ in compound AB is 4.
2. The coordination number of $A^{2+}$ in compound AB is 6.
3. The coordination number of $C^{+}$ in compound CD is 6.
4. The coordination number of $C^{+}$ in compound CD is 8.

Q. Given that density of $NaCl$ is nearly $2\times {10}^{3}kg{m}^{-3}$ and molecular weight is $58.5\times {10}^{-3}kgmo{l}^{-1}$. Then calculate the value of $a^3$ for unit cell of sodium chloride.
Here a is edge length of the fcc unit cell.

Take $N_A=6\times {10}^{23}$

1. $0.4\times {10}^{-30}{m}^3$
2. $3.5\times {10}^{-27}{m}^3$
3. $4.44\times {10}^{-29}{m}^3$
4. $1.95\times {10}^{-28}{m}^3$

Q. Which structure the compound will adopt if radius ratio is more than 1.0?

1. Cubic
2. Octahedral
3. Tetrahedral
4. Fcc

Q.

What do we mean by radius ratio?

1. Ratio of coordination number to radius of $Z_{eff}$

2. Ratio of radius of anion to radius of cation.

3. Ratio of radius of cation to radius of anion.

4. Ratio of $Z_{eff}$ to coordination number.

Q. $KCl$ crystallises in the same type of lattice as $NaCl$. Given that $r_{N{a}^{+}}/r_{C{l}^{-}}=0.50$ and $r_{N{a}^{+}}/r_{K^{+}}=0.70$, calculate the ratio of the side of the unit cell of $KCl$ to that of $NaCl$:

1. 1.143
2. 1.224
3. 1.414
4. 0.875

Q.

If the radius of $M{g}^{2+}$ is $6.5pm$ and $O_2^{-}$ is $14pm$, then calculate the coordination number of $M{g}^{2+}$ in the crystal of $MgO$.

1. 6

2. 5

3. 4

4. 3

Q.

If the radius ratio is between 0.225 - 0.414, what will be the type of void present. What will be the coordination number?

1. linear

2. tetrahedral - 4

3. tetrahedral - 2

4. octahedral

Q. If atom A ideally fit in tetrahedral voids formed by atoms of B of radius r then the minimum distance between centers of A and B will be:

1. 0.225r
   
2. 0.414r
   
3. 1.225r
   
4. 1.414r

Q.

If the radius ratio is between 0.414 - 0.732, what will be the type of void present? What will be the coordination number?

1. Tetrahedral - 4

2. Linear - 2

3. Octahedral - 6

4. Cubic - 8

Q. Pyrite ($Fe{S}_2$), crystallizes in a cubic unit cell with a cell edge of $0.540\text{nm}$. The density of pyrite is $5.02{\text{g/cm}}^3$. How many $F{e}^{2+}$ and $S_2^{2-}$ ions are present in a single unit cell? ($S=32\text{u},Fe=56\text{u}$)

1. $1F{e}^{2+}\text{and}1S_2^{2-}$
2. $2F{e}^{2+}\text{and}2S_2^{2-}$
3. $4F{e}^{2+}\text{and}4S_2^{2-}$
4. $6F{e}^{2+}\text{and}6S_2^{2-}$

Q. Given: Radius of $A^{2+}$ = 100 pm; Radius of $C^{+}$ = 240 pm; Radius of $B^{2-}$ = 300 pm; Radius of $D^{-}$ = 480 pm. Which is/are correct statement?

1. The coordination number of $A^{2+}$ in compound AB is 4.
2. The coordination number of $A^{2+}$ in compound AB is 6.
3. The coordination number of $C^{+}$ in compound CD is 6.
4. The coordination number of $C^{+}$ in compound CD is 8.

Q. I am Gingoo. My radius ratio is 0.325. Can you guess what is my structure?

1. Tetrahedral
2. Cubic
3. Octrahedral
4. Triangular

Q. $KCl$ crystalizes in the same type of lattice as $NaCl$.
Given that $\frac{r_{N{a}^{+}}}{r_{C{l}^{-}}}=0.5$ and $\frac{r_{K^{+}}}{r_{C{l}^{-}}}=0.65$ Then the ratio of the side of the unit cells for $KCl$ to that of $NaCl$ is:

1. 1.3
2. 3.3
3. 1.65
4. 1.1

Q. A compound AB has an $NaCl$ like structure. The radius of $A^{+}$ and $B^{-}$ is $1.14\stackrel{\circ }{A}$ and $1.86\stackrel{\circ }{A}$. What is the minimum distance between two $A^{+}$ ions in angstroms? (Take $\sqrt{2}$= 1.41)

Q. The metallic lustre exhibited by sodium is explained by:

1. Excitation of free protons
2. Oscillation of loose electrons
3. Existence of body centered cubic lattice
4. Diffusion of sodium ions

Q. $KCl$ crystallises in the same type of lattice as $NaCl$. Given that $r_{N{a}^{+}}/r_{C{l}^{-}}=0.50$ and $r_{N{a}^{+}}/r_{K^{+}}=0.70$, calculate the ratio of the side of the unit cell of $KCl$ to that of $NaCl$:

1. 1.143
2. 1.224
3. 1.414
4. 0.875

Q. Consider an ionic solid MX with $NaCl$ structure. Construct a new structure (Z) whose unit cell is constructed from the unit cell of MX following the sequential instructions given below. Neglect the charge balance.
(i) Remove all the anions (X) except the central one
(ii) Replace all the face centered cations (M) by anions (x)
(iii) Remove all the corner cations (M)
(iv) Replace the central anion (X) with cation (M)
The value of $\left(\frac{\text{number of anions}}{\text{number of cations}}\right)$ in Z is.

Q. Given: Radius of $A^{2+}=100\text{pm}$; Radius of $C^{+}=240\text{pm}$; Radius of $B^{2-}=300\text{pm}$; Radius of $D^{-}=480\text{pm}$. Which of the following statement(s) is/are correct?

1. Coordination number of $A^{2+}$ in the compound AB is 4
2. Coordination number of $A^{2+}$ in the compound AB is 6
3. Coordination number of $C^{+}$ in the compound CD is 6
4. Coordination number of $C^{+}$ in the compound CD is 8

Q. Choose the correct statement(s) :

Q. Given: Radius of $A^{2+}=100\text{pm}$; Radius of $C^{+}=240\text{pm}$; Radius of $B^{2-}=300\text{pm}$; Radius of $D^{-}=480\text{pm}$. Which of the following statement(s) is/are correct?

1. Coordination number of $A^{2+}$ in the compound AB is 4
2. Coordination number of $A^{2+}$ in the compound AB is 6
3. Coordination number of $C^{+}$ in the compound CD is 6
4. Coordination number of $C^{+}$ in the compound CD is 8