Introduction to Imperfections in Solids

Q. Which of the following is/are correct regarding defects in solids?

1. Metal excess defect is a stoichiometric defect
2. Stoichiometric defect is also called intrinsic defect
3. Point defects in crystal increase thermodynamic stability
4. All point defects result in decrease in the density of the solid

Q. Which of the following compounds is likely to show both Frenkel and Schottky defects in its crystalline form ?
(JEE Main 2020)

1. $ZnS$
2. $CsCl$
3. $AgBr$
4. $KBr$

Q. Consider a body centered cubic (BCC) arrangement, let $d_e,d_{fd},d_{bd}$ be the distances between successive atoms located along the edge, the face-diagonal, the body diagonal respectively in a unit cell. Their order is given by

1. $d_{bd}>d_e>d_{fd}$
2. $d_e<d_{fd}<d_{bd}$
3. $d_{fd}>d_{bd}>d_e$
4. $d_{bd}>d_{fd}>d_e$

Q. The approximate time duration in hours to electroplate $30g$ of calcium from molten calcium chloride using a current of $5A$ is (Atomic mass of $Ca=40g/mol$)

1. 10
2. 8
3. 80
4. 16

Q.
In the given sphere, the yellow spheres forms the first layer and red sphere forms the second layer and blue sphere forms the third layer.
The correct representation of the given arrangement of spheres is

1. bcc close packing
2. Square close packing
3. Hexagonal close packing
4. Cubic close packing

Q. Which of the following impurity should be doped with silicon to give p-type semiconductor?

Q. If the anion (A) forms hexagonal closest packing and cation (C) occupies only $\frac{2}{3}rd$ of octahedral voids in it, what will be the general formula of the compound?

Q. A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is ${}^{\prime }{a}^{\prime }$, the closest approach between two atoms in metallic crystal will be :
(JEE Main 2017)

Q. Vacancy defects and interstitial defect are shown by ionic solids

1. True
2. False

Q.

The non-stoichiometric compound $F{e}_{0.94}O$ is formed when x% of $F{e}^{2+}$ ions are replaced by as many $\frac{2}{3}F{e}^{3+}$ ions, x is ?

1. 6

2. 12

3. 15

4. 18

Q. The non-stoichimetric compound $F{e}_{0.94}O$ is formed when $x$% of $F{e}^{2+}$ ions are replaced by 2/3 $F{e}^{3+}$ ions, then $x$ is:

1. 18
2. 15
3. 12
4. 6

Q.

The correct statement(s) regarding defects in solids is / are

1. Frenkel defect is usually favoured by a very small difference in the sizes of cation and anion

2. Frenkel defect is a dislocation defect

3. trapping of an electron in the lattice leads to the formation of F-center

4. Schottky defects have no effect on the physical properties of solid

Q. The approximate time duration in hours to electroplate $30g$ of calcium from molten calcium chloride using a current of $5A$ is (Atomic mass of $Ca=40g/mol$)

1. 16
2. 10
3. 8
4. 80

Q. The three dimensional graph of lattice points which sets the pattern for the whole lattice is called :

1. Lattice point
2. Space lattice
3. Crystal lattice
4. Unit cell

Q.

A crystalline solid has

1. definite geometrical shape

2. flat faces

3. sharp edges

4. all of these

Q. Experimentally it was found that a metal oxide has formula $M_{0.98}O$. Metal $M$, is present as $M^{2+}$ and $M^{3+}$ in its oxide. Fraction of the metal which exists as $M^{3+}$ would be:

1. $4.08\%$
2. $6.05\%$
3. $5.08\%$
4. $7.01\%$