Voids

Q. A compound is formed by cation C and anion A. The anions form hexagonal close packed (hcp) lattice and the cations occupy 75% of octahedral voids. The formula of the compound is:

1. $C_3{A}_4$
2. $C_4{A}_3$
3. $C_3{A}_2$
4. $C_2{A}_3$

Q.

The structure of a mixed oxide is cubic close packed (ccp). The cubic unit cell of mixed oxide is composed of oxide ions. One-fourth of the tetrahedral voids are occupied by divalent metal A and the octahedral voids are occupied by a monovalent metal B. The formula of the oxide is

1. $AB{O}_2$

2. $A_{2}B{O}_2$

3. $A_2{B}_3{O}_4$

4. $A{B}_2{O}_2$

Q. Minimum distance between two tetrahedral voids if a is the edge length of the cube is Options: (1) a/2 (2) a/4 (3) a/2√2 (4) √3a/4

Q.

How many number of atoms are present in each unit cell in ccp structure?

Q.

The number of octahedral voids per lattice site in a lattice is __________

Q.

Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide .

Q.

A compound is formed by two elements M and N. The element N forms ccp and atoms of M occupy 1/3^rd of tetrahedral voids. What is the formula of the compound?

Q.

What is the number of octahedral voids in the BCC Unit cell?

Q.

Show that in a cubic packed structure, eight tetrahedral voids are present per unit cell.

Q.

What is the position of tetrahedral voids in FCC lattice?

1. Face center

2. edge center

3. √3a/4 distance from corners

4. body center

Q. Atoms of element B form HCP lattice and those of element A occupy two thirds of tetrahedral voids. The formula of the compound is .

1. $A_4{B}_3$
2. $A_4{B}_6$
3. $A_8{B}_3$

Q.

A compound AB crystallizes in bcc lattice with unit cell edge length of 480 pm. If radius of B- is 225 pm then radius of A+ is

Q.

Analysis shows that nickel oxide has the formula Ni_0.98O_1.00.What fractions of nickel exist as Ni²⁺and Ni³⁺ions?

Q.

The arrangement of $X^{-}$ ions around $A^{+}$ ion in solid AX is given in the figure (not drawn to scale). If the radius of $X^{-}$ is 250 pm, the radius of $A^{+}$ is

1. 125 pm

2. 57 pm

3. 104 pm

4. 183 pm

Q.

In which of the following arrangements octahedral voids are formed ?

(a) hcp (b) bcc (c) simple cubic (d) fcc

Q.

Why ccp structure is also called fcc structure ?

Q. The density of $Ca{F}_2$ is $3.180gc{m}^{-3}$ and edge length, a is $0.55nm$. Then number of particles $\left(Z_{eff}\right)$ in a unit cell are nearly :
Given :
$\text{Molar mass of}Ca{F}_2=78gmo{l}^{-1}$

1. 2
2. 4
3. 8
4. 12

Q. Consider the following statements. The correct statement is(are)

1. A monobasic acid with $K_a={10}^{-5}$ and a $pH=5$. The degree of dissociation of this acid is 50%.
2. The Le-Chatelier's principle is not applicable to commom-ion effect.
3. The pH of a mixture containing 400 mL of 0.1 M $H_{2}S{O}_4$ and 400 mL of 0.1 M $NaOH$ will be approximately 1.3.
4. Ionic product of water is temperature dependent.

Q. Iron exhibits bcc structure at room temperature. Above ${900}^{o}C$, it transforms to fcc structure. The ratio of density of iron at room temperature to that at ${900}^{o}C$ (assuming molar mass and atomic radii of iron remains constant with temperature) is:

1. $\frac{\sqrt{3}}{\sqrt{2}}$
2. $\frac{4\sqrt{3}}{3\sqrt{2}}$
3. $\frac{3\sqrt{3}}{4\sqrt{2}}$
4. $\frac{1}{2}$

Q. What is the critical radius ratio for the $CsCl$ structure?

Q. The density of a pure substance ‘A’, whose atoms are arranged in a cubic close pack arrangement, is $1\text{g/cc}$. If all the tetrahedral voids are now filled with ‘B’ atoms, what is the density of the resulting solid in $\text{g/cc}$? [Molar mass $A=30\text{g/mol}$ and Molar mass $\text{B = 50 g/mol}]$

1. 2.33
2. 5.33
3. 3.33
4. 4.33

Q.

Which of the following is not true about the voids formed in 3 dimensional hexagonal close packed structure ?

(a) A tetrehedral void is formed when a sphere of the second layer is present above triangular void in the first layer

(b) All the triangular voids are not covered by the spheres of the second layer

(c) Tetrahedral voids are formed when the triangular voids in the second layer lie above the triangular voids in the first layer and the triangulare shapes of these voids do not overlap

(d) Octahedral voids are formed when the triagular voids in th second layer exactly overlap with similar voids in the first layer

Q.

What is the number of Tetrahedral Void in CCP 3D structure?

Q. What is the coordination number of octahedral and tetrahedral voids in lattice ??

Q.

The ratio of close packed atoms to tetrahedral holes in cubic close packing is

1. 1 : 1

2. 1 : 2

3. 1 : 3

4. 2 : 1

Q. Calculate the molarity of a solution of ethanol in water, in which the mole fraction of ethanol is $0.040$ (assume the density of water to be one).

Q. A solid crystal is composed of X, Y and Z atoms. Y atoms are occupying 50% of octahedral voids, whereas X atoms are occupying the 100% tetrahedral void with Z atoms present in the ccp array arrangement, then the formula of the compound in the given crystal is

1. $X_{4}Y{Z}_2$
2. $X_{3}Y{Z}_2$
3. $X{Y}_4{Z}_2$
4. $X_5{Y}_{10}{Z}_8$

Q.

In a compound, nitrogen atoms (N) make cubic close packed lattic and metal atoms (M) occupy one-third of the tetrahedral voids present. Determine the formula of the compound formed by M and N ?

Q.

Which of the following is not true about the ionic solids ?

(a) Bigger ions form the close packed structure

(b) Smaller ions occupy either the tetrahedral or the octahedral voids depending upon their size

(c) Occupation of all the voids is not necessary

(d) The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids

Q. Why the number of tetrahedral voids are double than number of octahedral voids