Zeff

Q.

In a face-centred cubic lattice, atom (A) occupies the corner positions and atom (B) occupied the face centre positions. If one atom of (B) is missing from one of the face-centred points, the formula of the compound is

Q. In a cubic packed structure of mixed oxides, the lattice is made up of oxide ions, one-fifth of tetrahedral voids are occupied by X ion while half of the octahedral voids are occupied by Y ion. What will be the formula of oxide mixture?

1. $X{Y}_2{O}_4$
2. $X_5{Y}_4{O}_{10}$
3. $X_4{Y}_5{O}_{10}$
4. $X_{2}Y{O}_4$

Q.

The total number of atoms in a body centred cubic unit cell is

1. 1

2. 2

3. 3

4. 4

Q.

If the $Z_{eff}$ of cubes a, b and c is x, y and z respectively, find xyz. (For instance if x = 2, y = 3, z = 5, xyz = 235)

a)

b)

c)

___

Q.

The number of atoms in a primitive unit cubic cell is

1. 0

2. 1

3. 2
4. 3

Q.

The number of atoms in a unit cell of a FCC is

1. 1

2. 2

3. 3

4. 4

Q. A compound $\text{CuCl}$ has face-centred cubic structure. Its density is $3.05\text{g}{\text{cm}}^{-3}$. The length of unit cell is:
(Given, $N_A=6\times {10}^{23}$)

1. $6\stackrel{\circ }{\text{A}}$
   
2. $9\stackrel{\circ }{\text{A}}$
   
3. $12\stackrel{\circ }{\text{A}}$
4. $8\stackrel{\circ }{\text{A}}$

Q. A compound of formula $A_2{B}_3$ has a hcp lattice. Which atom forms the hcp lattice and what fraction of tetrahedral voids is occupied by the other atoms?

1. $B\to \text{hcp lattice}$;
   $A\to \frac{2}{3}\text{tetrahedral voids}$
2. $B\to \text{hcp lattice}$;
   $A\to \frac{1}{3}\text{tetrahedral voids}$
3. $A\to \text{hcp lattice}$;
   $B\to \frac{2}{3}\text{tetrahedral voids}$
4. $A\to \text{hcp lattice}$;
   $B\to \frac{1}{3}\text{tetrahedral voids}$

Q. A compound $M_p{X}_q$ has cubic close packing (ccp) arrangement of X. Its unit cell structure is shown below. The empirical formula of the compound is

1. MX
2. $M{X}_2$
3. $M_{2}X$
4. $M_5{X}_{14}$

Q.

Is $Z_{eff}$ the same in the following two cases?

1. True

2. False

Q. Na and Mg crystallize in BCC and FCC type crystals. The ratio of no. of atoms present in the unit cells of their respective crystals is:

1. 1:1
   
2. 1:2
   
3. 2:1
4. 1:4

Q.

Ferrous oxide has a cubic structure and each edge of the unit cell is 5.0 Å.

Assuming density of the oxide as , then the number of

ions present in each unit cell will be

[MP PET 2000]

1. Four and four
2. Two and four

3. Four and two

4. Three and three

Q. If the unit cell of a mineral has cubic close packed (ccp) array of oxygen atoms with $m$ fraction of octahedral holes occupied by aluminium ions and $n$ fraction of tetrahedral holes occupied by magnesium ions. $m$ and $n$ respectively are:

1. $1,\frac{1}{4}$

2. $\frac{1}{4},\frac{1}{8}$

3. $\frac{1}{2},\frac{1}{2}$

4. $\frac{1}{2},\frac{1}{8}$