MCQ 11 Mark
The edge length of a bcc unit cell of a metallic crystal is $2.9 \mathring A$. Hence the diameter of an atom is
- ✓
$1.025 \mathring A$
- B
$2.512 \mathring A$
- C
$1.45 \mathring A$
- D
$1.31 \mathring A$
AnswerCorrect option: A. $1.025 \mathring A$
View full question & answer→MCQ 21 Mark
What is the edge length of simple cubic unit cell if radius of atom is $174 \mathrm{pm}$ ?
- ✓
$348 \mathrm{pm}$
- B
$402 \mathrm{pm}$
- C
$492 \mathrm{pm}$
- D
$174 \mathrm{pm}$
AnswerCorrect option: A. $348 \mathrm{pm}$
View full question & answer→MCQ 31 Mark
Identify the type of unit cell containing single particle
MCQ 41 Mark
Calculate the molar mass of metal having density $7.8 \mathrm{~g} \mathrm{~cm}^{-3}$ and crystallizes to form bcc structure with edge length $288 \mathrm{pm}$.Q
- A
$120.0 \mathrm{~g} \mathrm{~mol}^{-1}$
- B
$86.2 \mathrm{~g} \mathrm{~mol}^{-1}$
- C
$108.1 \mathrm{~g} \mathrm{~mol}^{-1}$
- ✓
$56.1 \mathrm{~g} \mathrm{~mol}^{-1}$
AnswerCorrect option: D. $56.1 \mathrm{~g} \mathrm{~mol}^{-1}$
View full question & answer→MCQ 51 Mark
Lithium forms BCC structure having edge length of unit cell 351 pm then atomic radies of lithium is
MCQ 61 Mark
Edge length of unit cell of a crystal is $288 \mathrm{pm}$. If it's density is $7.2 \mathrm{~g} \mathrm{~cm}^{-3}$ determine the type of unit cell ( at. mass $=52$ ).
View full question & answer→MCQ 71 Mark
If $\mathrm{M}$ is atomic mass of element and a is edge length of unit cell then the formula to calculate density is
- A
$\rho=\frac{a^3 N_A}{n \times M}$
- B
$\rho=\frac{M N_A}{a^3 n}$
- C
$\rho=\frac{a^3 M}{n N_A}$
- ✓
$\rho=\frac{n M}{a^3 N_A}$
AnswerCorrect option: D. $\rho=\frac{n M}{a^3 N_A}$
View full question & answer→MCQ 81 Mark
Which among the following is NOT ferromagnetic in nature?
- ✓
$\mathrm{Zn}$
- B
$\mathrm{Ni}$
- C
$\mathrm{Co}$
- D
$\mathrm{Fe}$
AnswerCorrect option: A. $\mathrm{Zn}$
View full question & answer→MCQ 91 Mark
Which among the following statements is NOT true about covalent network solid?
- ✓
These are soft in nature.
- B
The atoms in this solid are linked by covalent bonds.
- C
In this solid the constituent particles are atoms.
- D
Covalent solids have high melting points.
AnswerCorrect option: A. These are soft in nature.
View full question & answer→MCQ 101 Mark
Which among the following statements is NOT true about Frenkel defect?
- A
The crystal as whole remains electrically neutral because equal number of cations and anions are present.
- B
The density of solid crystal and it's chemical properties remain unchanged as no ions are missing from the crystal lattice as a whole.
- ✓
It occurs in ionic compounds with sizes of cations and anions almos equal.
- D
The ions of ionic compound must have low co-ordination number.
AnswerCorrect option: C. It occurs in ionic compounds with sizes of cations and anions almos equal.
View full question & answer→MCQ 111 Mark
Calculate the number of unit cells in 3 gram metal that crystallises to simple cubic unit cell having edge length $336 \mathrm{pm}$. (density of metal $=9.4 \mathrm{~g} \mathrm{~cm}^{-3}$ )
- A
$7 \cdot 15 \times 10^{21}$
- B
$5 \cdot 82 \times 10^{21}$
- ✓
$8 \cdot 41 \times 10^{21}$
- D
$6 \cdot 25 \times 10^{21}$
AnswerCorrect option: C. $8 \cdot 41 \times 10^{21}$
View full question & answer→MCQ 121 Mark
Calculate the mass of bcc unit cell if metal has molar mass $56 \mathrm{~g} \mathrm{~mol}^{-1}$.
- ✓
$1.86 \times 10^{-22}$ gram
- B
$9.3 \times 10^{-24} \mathrm{gram}$
- C
$2.79 \times 10^{-24}$ gram
- D
$3.72 \times 10^{-22}$ gram
AnswerCorrect option: A. $1.86 \times 10^{-22}$ gram
View full question & answer→MCQ 131 Mark
What is the co-ordination number of a particle in fcc crystal lattice?
MCQ 141 Mark
Which of the following statements is NOT true about Schottky defect?
- A
It occurs in ionic compounds with sizes of cation and anion almost equal.
- B
The ions of ionic compound must have high co-ordination number.
- C
The density of substance decreases.
- ✓
The electrical neutrality of the compound is not preserved.
AnswerCorrect option: D. The electrical neutrality of the compound is not preserved.
View full question & answer→MCQ 151 Mark
Identify unit cell from following having four particles in it.
MCQ 161 Mark
Find the molar mass of an element that crystallizes forming unit cell structure having edge length $4 \times 10^{-8} \mathrm{~cm}$ and containing 4 particles. $\left(\mathrm{e}=19.7 \mathrm{~g} \mathrm{~cm}^{-3}\right)$
- A
$160 \cdot 5 \mathrm{~g} \mathrm{~mol}^{-1}$
- B
$220 \cdot 0 \mathrm{~g} \mathrm{~mol}^{-1}$
- C
$140 \cdot 2 \mathrm{~g} \mathrm{~mol}^{-1}$
- ✓
$189 \cdot 8 \mathrm{~g} \mathrm{~mol}^{-1}$
AnswerCorrect option: D. $189 \cdot 8 \mathrm{~g} \mathrm{~mol}^{-1}$
View full question & answer→MCQ 171 Mark
Calculate the density of metal with molar mass $56 \mathrm{~g} \mathrm{~mol}^{-1}$ that crystallises to form bcc structure with edge length $288 \mathrm{pm}$.
- A
$9.8 \mathrm{~g} \mathrm{~cm}^{-3}$
- B
$5.8 \mathrm{~g} \mathrm{~cm}^{-3}$
- C
$8.7 \mathrm{~g} \mathrm{~cm}^{-3}$
- ✓
$7.8 \mathrm{~g} \mathrm{~cm}^{-3}$
AnswerCorrect option: D. $7.8 \mathrm{~g} \mathrm{~cm}^{-3}$
View full question & answer→MCQ 181 Mark
What type of bonds are present in molecular crystals?
- ✓
Various inter molecular forces of attraction.
- B
- C
- D
AnswerCorrect option: A. Various inter molecular forces of attraction.
View full question & answer→MCQ 191 Mark
Which of the following statements is NOT true about ionic solid?
- A
In this constituent particles are held together by electrostatic force of attraction.
- B
The constituent particles of ionic solid are cations and anions.
- ✓
Pure ionic solid is good conductor of electricity in solid state.
- D
Ionic solids are hard and brittle.
AnswerCorrect option: C. Pure ionic solid is good conductor of electricity in solid state.
View full question & answer→MCQ 201 Mark
Calculate the volume of unit cell of element with density $7.2 \mathrm{~g} \mathrm{~cm}^{-3}$ that forms bcc structure. $(288$ gram of this element contains $3.35 \times 10^{24}$ atoms$)$
- ✓
$2.388 \times 10^{-23} \mathrm{~cm}^3$
- B
$3.912 \times 10^{-23} \mathrm{~cm}^3$
- C
$3.038 \times 10^{-23} \mathrm{~cm}^3$
- D
$4.136 \times 10^{-23} \mathrm{~cm}^3$
AnswerCorrect option: A. $2.388 \times 10^{-23} \mathrm{~cm}^3$
View full question & answer→MCQ 211 Mark
Which of the following is an example of ionic solid?
MCQ 221 Mark
Calculate the density of metal which forms simple cubic structure with edge length of unit cell $336 \mathrm{pm}$. (90 gram of meal contains $2.64 \times 10^{23}$ atoms)
- A
$7 \cdot 3 \mathrm{~g} \mathrm{~cm}^{-3}$
- ✓
$8.98 \mathrm{~g} \mathrm{~cm}^{-3}$
- C
$9.46 \mathrm{~g} \mathrm{~cm}^{-3}$
- D
$10.8 \mathrm{~g} \mathrm{~cm}^{-3}$
AnswerCorrect option: B. $8.98 \mathrm{~g} \mathrm{~cm}^{-3}$
View full question & answer→MCQ 231 Mark
What is the coordination number of sphere in simple cubic lattice?
MCQ 241 Mark
Calculate the density of an element with molar mass $27 \mathrm{~g} \mathrm{~mol}^{-1}$ having $4$ atoms in a unit cell with edge length $405 \mathrm{pm}$
- A
$3 \cdot 10 \mathrm{~g} \mathrm{~cm}^{-3}$
- B
$4.56 \mathrm{~g} \mathrm{~cm}^{-3}$
- C
$1.53 \mathrm{~g} \mathrm{~cm}^{-3}$
- ✓
$2.69 \mathrm{~g} \mathrm{~cm}^{-3}$
AnswerCorrect option: D. $2.69 \mathrm{~g} \mathrm{~cm}^{-3}$
View full question & answer→MCQ 251 Mark
What is the total volume occupied by atoms in bcc unit cell?
MCQ 261 Mark
What is the value of temperature in degree Celsius at absolute zero?
- A
$-373 \cdot 15^{\circ} \mathrm{C}$
- B
$0^{\circ} \mathrm{C}$
- C
$273\cdot 15^{\circ} \mathrm{C}$
- ✓
$-273 \cdot 15^{\circ} \mathrm{C}$
AnswerCorrect option: D. $-273 \cdot 15^{\circ} \mathrm{C}$
View full question & answer→MCQ 271 Mark
Calculate the density of metal having volume of unit cell $64 \times 10^{-24} \mathrm{~cm}^3$ and molar mass of metal $192 \mathrm{~g} \mathrm{~mol}^{-1}$ containing 4 particles in unit cell.
- A
$16.00 \mathrm{~g} \mathrm{~cm}^{-3}$
- ✓
$19.93 \mathrm{~g} \mathrm{~cm}^{-3}$
- C
$1492 \mathrm{~g} \mathrm{~cm}^{-3}$
- D
$18.00 \mathrm{~g} \mathrm{~cm}^{-3}$
AnswerCorrect option: B. $19.93 \mathrm{~g} \mathrm{~cm}^{-3}$
View full question & answer→MCQ 281 Mark
Calculate the number of atoms in $\mathbf{5}$ gram metal that crystallises to form simple cubic unit cell structure having edge length $336 \mathrm{pm}$.(density of metal $=9.4 \mathrm{~g} \mathrm{~cm}^{-3}$ )
- A
$2.1 \times 10^{22}$
- B
$1.8 \times 10^{22}$
- ✓
$1.4 \times 10^{22}$
- D
$1.0 \times 10^{22}$
AnswerCorrect option: C. $1.4 \times 10^{22}$
View full question & answer→MCQ 291 Mark
What is the void volume in the crystal lattice formed by bcc unit cell ?
MCQ 301 Mark
Calculate the molar mass of metal with density $1 \mathrm{gcm}^{-3}$ forming bcc structure with edge length $420 \mathrm{pm}$.
- ✓
$22 \cdot 3 \mathrm{~g} \mathrm{~mol}^{-1}$
- B
$25 \cdot 5 \mathrm{~g} \mathrm{~mol}^{-1}$
- C
$43 \cdot 3 \mathrm{~g} \mathrm{~mol}^{-1}$
- D
$32 \cdot 2 \mathrm{~g} \mathrm{~mol}^{-1}$
AnswerCorrect option: A. $22 \cdot 3 \mathrm{~g} \mathrm{~mol}^{-1}$
View full question & answer→MCQ 311 Mark
Calculate the volume of unit cell having four particles in it with density $19.0 \mathrm{~g} \mathrm{~cm}^{-3}\left[\right.$ molar mass of element $=190 \mathrm{~g} \mathrm{~mol}^{-1}$ ]
- ✓
$6.64 \times 10^{-23} \mathrm{~cm}^3$
- B
$3.32 \times 10^{-23} \mathrm{~cm}^3$
- C
$5.0 \times 10^{-23} \mathrm{~cm}^3$
- D
$2.4 \times 10^{-23} \mathrm{~cm}^3$
AnswerCorrect option: A. $6.64 \times 10^{-23} \mathrm{~cm}^3$
View full question & answer→MCQ 321 Mark
n-type semiconductor is formed when trace amount of impurity is added to silicon. The number of valence electrons in the impurity atom must be
MCQ 331 Mark
p-type semiconductor is formed when trace amount of impurity is added to silicon. The number of valence electrons in the impurity atom must be
MCQ 341 Mark
Semiconductors are manufactured by addition of impurities of
MCQ 351 Mark
For square close packing, the planar arrangement is
MCQ 361 Mark
The arrangement of layers in hexagonal close packing is
MCQ 371 Mark
An element crystallises in fee structure. If the atomic radius is 130 pm, the edge length of unit cell is
MCQ 381 Mark
The edge length of a bcc unit cell of a metallic crystal is 2.9 Å. Hence the diameter of an atom is
MCQ 391 Mark
An element having atomic mass 115 u, crystallises in bcc structure. The number of unit cells in 1 g of the element will be
- ✓
$2.6 \times 10^{21}$
- B
$3.8 \times 10^{23}$
- C
$8.7 \times 10^{-3}$
- D
$6.17 \times 10^{20}$
AnswerCorrect option: A. $2.6 \times 10^{21}$
View full question & answer→MCQ 401 Mark
The unit cell has an edge length 403 pm. The distance between two atoms placed opposite ends of body diagonal will be
MCQ 411 Mark
Edge length of a cubic unit cell is 354 pm. The distance between two atoms diagonally opposite on the face is
MCQ 421 Mark
An element crystallises in fee structure. If the atomic mass of the element is 72.7 U, the mass of one unit cell of it will be
AnswerCorrect option: B. $4.83 \times 10^{-25} kg$
View full question & answer→MCQ 431 Mark
Stron The mass of a unit cell of a body centred cubic crystal of a metal is $72.2 \times 10^{-23} g$. The atomic mass of the metal is
- A
$128.6 gmol ^{-1}$
- B
$108.7 gmol ^{-1}$
- ✓
$217.3 gmol ^{-1}$
- D
$57.86 gmol ^{-1}$
AnswerCorrect option: C. $217.3 gmol ^{-1}$
View full question & answer→MCQ 441 Mark
Gold crystallises in face centred cubic structure. If atomic mass of gold is $197 g mol ^{-1}$, the mass of the unit cell of gold will be
AnswerCorrect option: D. $1.3 \times 10^{-24} kg$
View full question & answer→MCQ 451 Mark
If all the lattice points in ccp structure namely comers, face and edge centres and body centre are occupied by atoms then the total number of atoms in the unit cell will be
MCQ 461 Mark
Copper crystallises in face centred cubic structure. If the unit cell length is 360 pm, the radius of copper atom is
MCQ 471 Mark
The volume of unit cell of a metallic crystal of bcc type is $8.4 \times 10-23 cm 3$. The volume occupied by $10$ atoms in the crystalline structure is
- A
$4.2 \times 10^{-22} cm^3$
- B
$3.12 \times 10^{-23} cm^3$
- C
$1.74 \times 10^{-23} cm^3$
- ✓
$2.856 \times 10^{-22} cm^3$
AnswerCorrect option: D. $2.856 \times 10^{-22} cm^3$
View full question & answer→MCQ 481 Mark
A metallic element crystallises in face centred cubic structure. If the radius of metal ion is 0.92 Å, the edge length of the unit cell of the crystal is
MCQ 491 Mark
$CrO _2$ is
View full question & answer→MCQ 501 Mark
The substances which can be permanently magnetised are
MCQ 511 Mark
The volume of atoms present in body centred cubic unit cell of a metal of atomic radius r is,
- A
$\frac{16}{3} \pi r^3$
- ✓
$\frac{8}{3} \pi r^3$
- C
$\frac{12}{3} \pi r^3$
- D
$\frac{24}{3} \pi r^3$
AnswerCorrect option: B. $\frac{8}{3} \pi r^3$
View full question & answer→MCQ 521 Mark
Total number of different primitive unit cells are
MCQ 531 Mark
An ionic compound crystallises in FCC type structure with ‘A’ ions at the centre of each face and ‘B’ ions occupying comers of the cube. The formula of compound is
- A
$AB _4$
- ✓
$A _3 B$
- C
$AB$
- D
$AB _3$
AnswerCorrect option: B. $A _3 B$
View full question & answer→MCQ 541 Mark
Schottky defects are observed in which solid among the following ?
MCQ 551 Mark
The type of defect in NaCl crystal will be
MCQ 561 Mark
An ionic solid crystallises in bcc structure. If the ionic radii of cation and anion are 0.84 Å and 1.07 Å, the length of the body diagonal is
MCQ 571 Mark
A defect present in AgCl is
- ✓
- B
- C
- D
interstitial impurity defect
View full question & answer→MCQ 581 Mark
The ratio of close packed atoms to octahedral holes in cubic packing is
MCQ 591 Mark
The major binding force in diamond is
MCQ 601 Mark
The correct sequence of the atomic layers in cubic close packing is
MCQ 611 Mark
The ratio of packing efficiency in see, bcc and fee crystalline structures is
MCQ 621 Mark
If r is the radius of an atom and a is an edge length of fcc unit cell, then
- A
$r=\frac{\sqrt{3}}{4} a$
- ✓
$r=\frac{a}{2 \sqrt{2}}$
- C
$r=\frac{a}{2}$
- D
$r=2 \sqrt{2} a$
AnswerCorrect option: B. $r=\frac{a}{2 \sqrt{2}}$
View full question & answer→MCQ 631 Mark
The packing fraction for a body centred cubic structure is
MCQ 641 Mark
The number of tetrahedral sites per sphere in ccp structure is,
MCQ 651 Mark
Face centred cubic crystal is
- A
Cubic lattice of Bravais system
- B
- ✓
Bravais lattice of cubic system
- D
Cubic lattice with 5 atoms
AnswerCorrect option: C. Bravais lattice of cubic system
View full question & answer→MCQ 661 Mark
The number of Bravais lattices are
MCQ 671 Mark
The number of crystal systems (or types) is
MCQ 681 Mark
Anisotropy is observed in
AnswerCorrect option: C. $K _2 SO _4$
View full question & answer→MCQ 691 Mark
View full question & answer→MCQ 701 Mark
A single substance that exists in two or more forms is called
MCQ 711 Mark
In solids the constituent particles may be
- A
- B
- C
- ✓
any one of the above three
AnswerCorrect option: D. any one of the above three
View full question & answer→MCQ 721 Mark
A solid which has definite heat of fusion is
AnswerCorrect option: B. $CaCl _2$
View full question & answer→MCQ 731 Mark
A substance which on cutting will give irregular cleavage is
MCQ 741 Mark
Pb has fcc structure with edge length of unit cell 495 pm. Radius of Pb atom is
MCQ 751 Mark
A compound forms hcp structure. Number of octahedral and tetrahedral voids in $0.5 mole$ of substance is respectively
- ✓
$3.011 \times 10^{23}, 6.022 \times 10^{23}$
- B
$6.022 \times 10^{23}, 3.011 \times 10^{23}$
- C
$4.011 \times 10^{23}, 2.011 \times 10^{23}$
- D
$6.011 \times 10^{23}, 12.022 \times 10^{23}$
AnswerCorrect option: A. $3.011 \times 10^{23}, 6.022 \times 10^{23}$
View full question & answer→MCQ 761 Mark
Which of the following is not correct ?
- A
Four spheres are involved in the formation of tetrahedral void.
- B
The centres of spheres in octahedral voids are at the a pices of a regular tetrahedron.
- ✓
If the number of atoms is N the number of octahedral voids is 2N.
- D
If the number of atoms is N/2, the number of tetrahedral voids is N.
AnswerCorrect option: C. If the number of atoms is N the number of octahedral voids is 2N.
If the number of atoms is N the number of octahedral voids is 2N.
View full question & answer→MCQ 771 Mark
The coordination number of atoms in bcc crystal lattice is
MCQ 781 Mark
In crystal lattice formed by bcc unit cell the void volume is
MCQ 791 Mark
- A
electrical neutrality of the substance is changed.
- B
density of the substance is changed.
- C
both cation and anion are missing
- ✓
overall electrical neutrality is preserved
AnswerCorrect option: D. overall electrical neutrality is preserved
View full question & answer→MCQ 801 Mark
Which of the following is n-type semiconductor?
MCQ 811 Mark
View full question & answer→MCQ 821 Mark
Find the radius of metal atom in simple cubic unit cell having edge length $334.7 pm$ ?
- ✓
$167.35 pm$
- B
$334.70 pm$
- C
$144.93 pm$
- D
$118.32 pm$
AnswerCorrect option: A. $167.35 pm$
(a) : For simple cubic cell, edge length, $a=2 r$
334.7 $pm =2 r$
$
\Rightarrow r=\frac{334.7 pm }{2}=167.35 pm
$
View full question & answer→MCQ 831 Mark
Which from following metal has ccp crystal structure?
Answer(a) : Copper, siher and gold have acp crystal structure.
View full question & answer→MCQ 841 Mark
What is the number of unit cells when one mole atom of a metal, that forms simple cubic structure?
- ✓
$6.022 \times 10^{23}$
- B
$1.204 \times 10^{24}$
- C
$9.033 \times 10^{23}$
- D
$3.011 \times 10^{23}$
AnswerCorrect option: A. $6.022 \times 10^{23}$
(a) : A simple cubic crystal unit cell has 8 atoms at its corner. The total number of atoms in the unit cell is $8 \times \frac{1}{8}=1$ atom. For one mole of atom, $N_A$ number of unit cells are present i.c., $6.022 \times 10^{23}$.
View full question & answer→MCQ 851 Mark
What is the packing efficiency of silver metal in its unit cell?
- A
$52.4 \%$
- B
$68.0 \%$
- C
$32.0 \%$
- ✓
$74.0 \%$
AnswerCorrect option: D. $74.0 \%$
(d) : Silver crystallises in foc crystal structure and packing efficiency of foc (or ccp) is $74 \%$.
View full question & answer→MCQ 861 Mark
A compound made of elements $A$ and $B$ form $f c c$ structure. Atoms of $A$ are at the corners and atoms of $B$ are present at the centres of faces of cube. What is the formula of the compound?
- A
$A B$
- B
$A B_2$
- ✓
$A B_3$
- D
$A_2 B$
AnswerCorrect option: C. $A B_3$
(c) : A face-centred cubic unit cell contains atoms at the comer and at the centre of all faces of the cube. There are total 8 corners and each contributes one-eighth to the unit cell. As, $A$ atoms are present at corners.
Total $A$ atoms in a unit cell $=8 \times \frac{1}{8}=1$
There are 6 face-centres and each contributes one-half to the unit cell. As, $B$ atoms are present at face-centres,
Total $B$ atoms in a unit cell $=6 \times \frac{1}{2}=3$
Thus, the formula of the compound is $A B_3$.
View full question & answer→MCQ 871 Mark
Calculate the edge length of $b c c$ unit cell if radius of metal atom is $227 pm$.
AnswerCorrect option: B. $5.24 \times 10^{-8} cm$
(b) $: r=227 pm$
For bec crysial, $\frac{\sqrt{3}}{4} a=r$ $a=\frac{4 r}{\sqrt{3}}=\frac{4 \times 227}{\sqrt{3}}=5.24 \times 10^{-8} cm$
View full question & answer→MCQ 881 Mark
Which from following combinations is an example for construction of $n$-type semiconductor?
Answer(b) : Group 14 element (Si) is doped with group 15 element $( P$ ) in n-type semiconductors.
View full question & answer→MCQ 891 Mark
Which among the following elements does not exhibit ferromagnetic properties?
Answer(a) ; $Fe , Co$ and $Ni$ are ferromagnetic substances, Chromium (Cr) is not a ferromagnetic substance.
View full question & answer→MCQ 901 Mark
Calculate the density of metal having molar mass $210 g mol ^{-1}$ that forms simple cubic unit cell $\left(a^3 \cdot N_A=21.5 cm ^3 mol ^{-1}\right)$
- ✓
$9.77 g cm ^{-3}$
- B
$7.15 g cm ^{-3}$
- C
$8.12 g cm ^{-3}$
- D
$6.94 g cm ^{-3}$
AnswerCorrect option: A. $9.77 g cm ^{-3}$
(a) : $M=210 g mol ^{-3} ; a^3 \cdot N_A=21.5 cm ^3 mol ^{-1}$
$Z=1$ (For simple cubic)
$d=\frac{Z \cdot M}{a^3 \cdot N_A}=\frac{1 \times 210}{21.5}=9.77 g cm ^{-3}$
View full question & answer→MCQ 911 Mark
Calculate the volume of unit cell if an element having molar mass $56 g mol ^{-1}$ that forms $b c c$ unit cells. $\left[\rho . N_A=4.8 \times 10^{24} g cm ^{-3} mol ^{-1}\right]$
- A
$1.17 \times 10^{-23} cm ^3$
- B
$4.79 \times 10^{-23} cm ^3$
- C
$3.31 \times 10^{-23} cm ^3$
- ✓
$2.33 \times 10^{-23} cm ^3$
AnswerCorrect option: D. $2.33 \times 10^{-23} cm ^3$
(d) $: \rho=\frac{Z \times M}{N_4 a^3}, Z=2$ (For bcc)
$\Rightarrow a^3=\frac{Z \times M}{N_d \rho}=\frac{2 \times 56}{4.8 \times 10^{24}}=2.33 \times 10^{-23} cm ^3$
View full question & answer→MCQ 921 Mark
In an ionic crystalline solid atoms of element $Y$ forms hcp structure. The atoms of element $X$ occupy one third of tetrahedral voids. What is the formula of compound?
- ✓
$X_2 Y_3$
- B
$X Y$
- C
$X_3 Y_2$
- D
$X Y_2$
AnswerCorrect option: A. $X_2 Y_3$
(a) : Let the number of $Y$ atoms $=n$
The number of $X$ atoms $=2 n \times \frac{1}{3}=\frac{2 n}{3}$
$\therefore$ Formula of cempound $=X_{\frac{2 v}{3}} Y_n=X_2 Y_3$
View full question & answer→MCQ 931 Mark
What is total number of crystal systems associated with 14 Bravais lattices?
Answer(a) $: 7$ crystal systems are associated with 14 Bravais lattices.
View full question & answer→MCQ 941 Mark
Which of the following statements is not true about polymorphism?
MCQ 951 Mark
Calculate the number of unit cells in 3 gram metal that crystallises to simple cubic unit cell having edge length $336 pm$. (density of metal $=9.4 g cm ^{-3}$ )
- ✓
$8.41 \times 10^{21}$
- B
$6.25 \times 10^{21}$
- C
$7.15 \times 10^{21}$
- D
$5.82 \times 10^{21}$
AnswerCorrect option: A. $8.41 \times 10^{21}$
(a) : Valume of the unit cell $=(336 pm )^3$
$
=\left(336 \times 10^{-10} cm \right)^3=3.8 \times 10^{-23} cm ^3
$
Volume of $3 g$ of the element $=\frac{\text { Mass }}{\text { Density }}$
$
=\frac{3 g }{9.4 g ^{\prime} cm ^3}=0.32 cm ^3
$
$\therefore \quad$ Number of unit cells in this volume
$
=\frac{0.32}{3.8 \times 10^{-23}}=0.0842 \times 10^{23}=8.42 \times 10^{21}
$
View full question & answer→MCQ 961 Mark
The substances which are weakly repelled by the magnetic field are
MCQ 971 Mark
Percentages of free space in cubic close packed structure and in body centred packed structure are respectively
- A
$32 \%$ and $48 \%$
- B
$48 \%$ and $26 \%$
- C
$30 \%$ and $26 \%$
- ✓
$26 \%$ and $32 \%$
AnswerCorrect option: D. $26 \%$ and $32 \%$
(d): Percentages of free space in $\alpha c p$ and boc are respectively $26 \%$ and $32 \%$.
View full question & answer→MCQ 981 Mark
Which among the following compounds in crystalline form is used for making Nicol's prism?
- A
$CaSO _4$
- B
$Na _2 AlF _6$
- C
$CaCO _3$
- D
$Al _2 O _3$
View full question & answer→MCQ 991 Mark
Which among the following metals crystallises as a simple cube?
Answer(a) : Polonium crystallises in a simple cubic structure.
View full question & answer→MCQ 1001 Mark
Which among the following solids is a non polar solid?
MCQ 1011 Mark
Which halide of magnesium has highest ionic character?
Answer(d) : Smaller the anion and higher its electronegativity, greater is the ionic character:
View full question & answer→MCQ 1021 Mark
In face centered cubic unit cell, what is the volume occupied?
AnswerCorrect option: C. $\frac{16}{3} \pi r^3$
(c) : In face centered cubic unit cell, there are four atoms and their volume is given by
$
y=4 \times\left[\frac{4 \pi v^3}{3}\right]=\frac{16 \pi v^3}{3}
$
View full question & answer→MCQ 1031 Mark
Which metal crystallises in a simple cubic structure?
Answer(a) : Polonium crystallises in a simple cubic structure. Copper and nickel crystallise in facecentered cubic structure. Iron crystallises in a body-centered cubic structure.
View full question & answer→MCQ 1041 Mark
Which metal among the following has the highest packing efficiency?
Answer(c) :
| Element | Lattice type | Packing efficiency |
| Iron, Tungsten | bcc lattice | 68% |
| Aluminium | ccp/fcc | 74% |
| Polonium | Simple cubic | 52.4% |
View full question & answer→MCQ 1051 Mark
Select a ferromagnetic material from the following.
Answer(b) : Dioxygen - Paramagnetic
Chromium(IV) oxide - Ferromagnetic
Benzene - Diamagnetic
Dihydrogen monoxide $\left( H _2 O \right)$ - Diamagnetic
View full question & answer→MCQ 1061 Mark
Which among the following solids crystallises as a face-centred cube?
Answer(d) ; Fe, Rb, U-bcc; Pt-foc
View full question & answer→MCQ 1071 Mark
Which statement is not correct about fullerene $C _{60}$ ?
- A
It contains $20$ six$-$membered rings and $12$ fivemembered rings.
- B
All carbon atoms undergo $s p^2-$hybridization.
- C
A six$-$membered ring is fused with six$-$membered ring only.
- D
A five$-$membered ring is fused with six$-$membered ring only.
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