The Solid State Quiz-5

The Solid State Quiz-5

Dear Readers,

IIT JEE exam which consists of JEE Main and JEE Advanced is one of the most important entrance exams for engineering aspirants. The exam is held for candidates who are aspiring to pursue a career in the field of engineering and technical studies. Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..

Q1.Silicon dopped with group 13 and group 15 member elements is, respectively, called……semiconductor :

•  p-type, n-type
•  n-type, p-type
•  p-type
•  n-type

Solution
(a) p-type (factual statement)

Q2.A solid has a structure in which W atoms are located at the corners of a cubic lattice, Oatoms at the center of edges, and Na atom at the center of the cube. The formula of the compound is :

•  NaWO2
•  NaWO3
•  Na2WO3
•  NaWO4

Solution
(b) W atoms/unit cell =8×1/8=1 O atoms/unit cell =12×1/4=3 Na atoms/unit cell =1 Hence, formula is NaWO3

Q3.  In which of the following crystals alternate tetrahedral voids are occupied?

•  NaCl
•  Zns
•  CaF2
•  Na2O

Solution
(b) In ZnS structure, sulphide ions occupy all (fcc) lattice points while Zn2+ ions are present in alternate tetrahedral sites. Therefore, there is one Zn2+ ion for every S2- ion

Q4. Two ionic solids AB and CB crystallize in the same lattice. If rA/rB⊝ and rC/rB⊝ are 0.50 and 0.70, respectively, then the ratio of edge length of AB and CD is

•  0.68
•  0.78
•  0.88
•  0.98

Solution
(c) rA⨁/rB⊝=0.50 and rC⨁/rB⊝=0.70 (rA+rB) / rB⊝=1+0.5=1.5 Similarly, rC+rB⊝/rB⊝=1.70 ∴rA+rB⊝/rC+rB⊝=1.5/1.7=0.88 Also, aAB=2rA+rB⊝andaCB=2rC+rB⊝ ∴aABaCB=1.51.7=0.88

Q5.In an fcc unit cell, atoms are numbered as shown below. The atoms not touching each other are (Atom numbered 3 is face center of front face)

 

•  3 and 4
•  1 and 3
•  1 and 2
•  2 and 4

Solution
 (c) In fcc structure, corner atoms do not touch each other (atoms 1 and 2), but every face center atom touches corners. Moreover, every face center atom touched every other face center atom provided it is not the opposite face center atom in an fcc unit cell Atoms 3 and 4 are touching each other where center-to-center distance =a/root(2) Atoms 1 and 2 are not touching each other Atoms 2 and 4 are touching each other where center-to-center distance =a/root(2)

Q6. What is the density of Na2O having antifluorite-type crystal structure, if the edge length of cube is 100 pm and what is the effect on density by 0.05% Frenkel defect?

•  823.5 g cm-3, density decrease
•  414.16 g cm-3, density decreases
•  823.5 g cm-3, density remains same
•  414.16 g cm-3, density remains same

Solution
(d) Density =Zeff*Mw/NA*a3 (For antifluorite, Zeff=4/unit cell) =4×23×2+166×1023100 pm×10-10cm3 1 pm=10-12m =10-10 cm =414.16 g cm-3 Note: Frenkel defect does not change the density of the crystal

Q7.An fcc lattice has a lattice parameter a= 400 pm. Calculate the molar volume of the lattice including all the empty space

•  10.8 mL
•  96 mL
•  8.6 mL
•  9.6 mL

Solution
(d) Number of atoms =NA Number of unit cells =NA4 [∵4 atoms in each unit cell] Volume of 1 mol lattice = NA/4 Volume of unit cell =6.023×10^23/4 * (400×10^-12)^3 =9.64 mL

Q8.Which of the following metal oxides is anti-ferromagnetic in nature?

•  MnO2
•  TiO2
•  VO2
•  CrO2

Solution
(a) Factual statement

Q9.In the cubic lattice given below, the three distances between the atoms A-B, A-C, and A-Gare, respectively,

 

•  a,root(2)a,root(3)a
•  a,root(3)a,root(2)a
•  a/2,a/root(2),root(3)a/2
•  a,root(3)a/2,root(2)a

Solution
(a) Edge length= AB=AD=BC=CD=a AC=root(AB^2+BC^2)=root(a^2+a^2)=root(2)a AG=root(AC^2+CG^2)=root(2a^2+a^2)=root(3)a

Q10.Which of the following figures represents the cross-section of an OV?

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Solution
(a)