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Chemistry M.C.Q (1 Marks)

The Solid State · Gujarat Board (GSEB) STD 12 Science (GSEB - English Medium). 156 questions.

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M.C.Q (1 Marks)

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50 questions · auto-graded multiple-choice test.

MCQ 11 Mark
Silicon doped with electron-rich impurity forms ________.
  • A
    p-type semiconductor.
  • ✓
    n-type semiconductor.
  • C
    Intrinsic semiconductor.
  • D
    Insulator.
Answer
Correct option: B.
n-type semiconductor.
Explanation: (B) n-type semiconductor.
When silicon is doped with electron rich impurity like P or As, the increase in conductivity is due to the negatively charged Electron. Hence, silicon doped with electron rich impurity is termed as 'n-type semiconductor'.
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MCQ 31 Mark
Which of the following arrangements correctly represents hexagonal and cubic close packed structure respectively?
  • ✓
    $\text{ABAB}.....$ and $\text{ABCABCABC}.....$
  • B
    $\text{ABCABC}.....$ and $\text{ABAB}....$
  • C
    Both have $\text{ABCABC}......$ arrangement
  • D
    Both have $\text{ABAB}...$ arrangement
Answer
Correct option: A.
$\text{ABAB}.....$ and $\text{ABCABCABC}.....$
$\text{ABAB}....$ and $\text{ACBACB}.....$ arrangements correctly represents hexagonal and cubic close$-$packed structure respectively.
Note$:\ \text{AAAA}$ type arrangement represents simple cubic structure.
$\text{ACBACB}.....$ arrangement can also be represented as $\text{ABCABC}......$ arrangement.
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MCQ 41 Mark
When a viscous liquid is cooled rapidly $.......$ solid is formed.
  • A
    Eutectic
  • B
    Liquid crystal
  • C
    Super$-$cooled
  • ✓
    Amorphous
Answer
Correct option: D.
Amorphous
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MCQ 51 Mark
A solid can be irreversibly deformed. The stamping of sheets of steel into 'fins' of motor cars is a case of :
  • A
    Vaccum deformation
  • ✓
    Plastic deformation
  • C
    Elastic deformation
  • D
    Flexible shaping
Answer
Correct option: B.
Plastic deformation
Plastic Deformation is the permanent distortion which occurs when the material is subjected to stress, tensile or compression that exceeds its yield strength.
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MCQ 61 Mark
In which of the following type of lattices, the coordination number is $4\ ?$
  • A
    $\text{BCC}$
  • B
    Simple cubic
  • C
    $\text{HCP}$
  • ✓
    $\text{FCC}$
Answer
Correct option: D.
$\text{FCC}$
In Face centered cubic structure octahedral voids are located at:
  • Body Center
  • Edge Centers
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MCQ 71 Mark
The pink colour of lithium chloride crystal is due to:
  • A
    Frenkel defect
  • ✓
    Metal excess defect
  • C
    Metal deficiency defect
  • D
    Impurity defect
Answer
Correct option: B.
Metal excess defect
$\text{iCl}$ has non$-$stochiometric metal excess defect due to anion vacancies. The negative ions $(Cl^-)$ are missing from their lattice sites leaving the holes in which electrons are entrapped so that electrical neutrality is maintained.
When $\text{LiCl}$ is heated$, Li$ atoms gets deposited on the surface of the crystal. The $Cl^-$ ions diffuse into the surface and combine with $Li$ atoms to give $\text{LiCl}.$ This is so because of loss of electrons by $Li$ atoms to form $Li^+$. The released electrons diffuse excess into crystal and occupy anionic sites. As a result, there is an excess of $Li.$ The anionic sites occupied by unpaired electrons are $F-$centers which imparts a pink color to $\text{LiCl}$ crystals. The color is observed as a result of excitation of these electrons when they absorb energy from visible light falling on crystals.
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MCQ 81 Mark
Which metal crystallises in a simple cubic structure?
  • ✓
    Polonium
  • B
    Copper
  • C
    Nickel
  • D
    Iron
Answer
Correct option: A.
Polonium
Polonium crystallises in a simple cubic structure.
Copper and Nickel crystallises in a face centred cubic structure.
Iron crystallises in a body centred cubic structure.
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MCQ 91 Mark
$P-$type semi$-$conductors are made by mixing silicon with impurities of:
  • A
    germanium
  • ✓
    boron
  • C
    arsenic
  • D
    antimony
Answer
Correct option: B.
boron
Since boron has $3$ electrons in its valence shell, it offers $3$ of the four electrons that a silicon atom needs.
As a result, each silicon center is left with a hole. Semiconductors made in this manner are called $p-$type.
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MCQ 101 Mark
Which one of the following is not a close packing?
  • A
    $\text{HCP}$
  • B
    $\text{CCP}$
  • ✓
    $\text{BCC}$
  • D
    $\text{FCC}$
Answer
Correct option: C.
$\text{BCC}$
The space occupied in $\text{hcp, ccp, bcc}$ and $\text{fcc}$ structures are $74\%, 74\%, 68\%$ and $74\%$ respectively. Thus$, \text{bcc}$ is not a close packing.
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MCQ 111 Mark
Amorphous solid can also be called $............$
  • A
    Pseudo solids.
  • B
    True solids.
  • ✓
    Super cooled liquids.
  • D
    Super cooled solids.
Answer
Correct option: C.
Super cooled liquids.
Amorphous solid has short range order which has a tendency to flow very slowly. Hence, it is also known as pseudo solids or super cooled liquids. Glass panes fixed to windows or doors of old buildings are invariably observed to be thicker at bottom than at the top. These are examples of amorphous solids.
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MCQ 121 Mark
Which metal among the following has the highest packing efficiency?
  • A
    Iron
  • B
    Tungsten
  • ✓
    Aluminium
  • D
    Polonium
Answer
Correct option: C.
Aluminium
The packing efficiency is is the fraction of volume in a crystal structure that is occupied by constituent particles $($volume of space occupied by the spheres/ total volume$).$ The majority of metals take on either the $\text{hcp}$ or $\text{bcc}$ structure. Among the given metals Al occupies hexagonal close$-$packed $(\text{hcp})$ is having $0.74$ packing efficiency and other metals form body$-$centered cubic $(\text{bcc})$ which has $0.68$ packing efficiency.
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MCQ 131 Mark
In which pair most efficient packing in present?
  • A
    $\text{Hcp}$ and $\text{bcc}$
  • ✓
    $\text{Hcp}$ and $\text{ccp}$
  • C
    $\text{Bcc}$ and $\text{ccp}$
  • D
    $\text{Bcc}$ and simple cubic cell
Answer
Correct option: B.
$\text{Hcp}$ and $\text{ccp}$
The packing efficiency of the lattices are given below.
$\text{hcp} = 74\%$
$\text{ccp} = 74\%$
$\text{bcc} = 68\%$
Simple cubic $= 54\%.$
So, the pair with most efficient packing is $\text{hcp}$ and $\text{ccp}.$
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MCQ 141 Mark
Which of the following statements are true about semiconductors?
  1. Silicon doped with electron rich impurity is a $p-$type semiconductor.
  2. Silicon doped with an electron rich impurity is an $n-$type semiconductor.
  3. Delocalised electrons increase the conductivity of doped silicon.
  4. An electron vacancy increases the conductivity of $n-$type semiconductor.
  • ✓
    $2$ and $3$
  • B
    $1$ and  $2$
  • C
    $3$ and  $4$
  • D
    $1$ and  $4$
Answer
Correct option: A.
$2$ and $3$
Silicon $($valence electron $- 4)$ doped with electron rich impurity is an $n-$type semiconductor due to extra electron and the delocalised electrons increase the conductivity of doped silicon.
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MCQ 151 Mark
In which of the following structures coordination number for cations and anions in the packed structure will be same?
  • ✓
    $Cl ^{-}$ ion form fcc lattice and Na$^{+}$ ions occupy all octahedral voids of the unit cell.
  • B
    Ca$^{2+}$ ions form fcc lattice and F$^{-}$ ions occupy all the eight tetrahedral voids of the unit cell.
  • C
    $O ^{2-}$ ions form fcc lattice and $Na ^{+}$ions occupy all the eight tetrahedral voids of the unit cell.
  • D
    $S ^{2-}$ ions form fcc lattice and $Zn ^{2+}$ ions go into alternate tetrahedral voids of the unit cell.
Answer
Correct option: A.
$Cl ^{-}$ ion form fcc lattice and Na$^{+}$ ions occupy all octahedral voids of the unit cell.
a. $Cl ^{-}$ion form fcc lattice and $Na ^{+}$ions occupy all octahedral voids of the unit cell.
Explanation:
NaCl crystals have rock salt structure having fee lattice in which $Cl ^{-}$ions are present at fee lattice points and face centre and $Na ^{+}$occupies all the octahedral voids of given unit cell.
Where, coordination number of $Na ^{+}=6$
Coordination number of $Cl ^{-}=6$


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MCQ 161 Mark
The sharp melting point of crystalline solids is due to $.......$
  • A
    a regular arrangement of constituent particles observed over a short distance in crystal lattice.
  • ✓
    a regular arrangement of constituent particles observed over a long distance in crystal lattice.
  • C
    same arrangement of constituent particles in different direction
  • D
    different arrangement of constituent particles in different directions
Answer
Correct option: B.
a regular arrangement of constituent particles observed over a long distance in crystal lattice.
Crystals tend to have relatively sharp, well$-$defined melting points because all the component atoms, molecules, or ions are the same distance from the same number and type of neighbors; that is, the regularity of the crystalline lattice creates local environments that are the same.
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MCQ 171 Mark
Which of the following solids is not an electrical conductor?
$A. \mathrm{Mg}(\mathrm{s}).$
$B. \mathrm{TiO}(\mathrm{s}).$
$C. \mathrm{I}_2(\mathrm{~s}).$
$D. \mathrm{H}_2 \mathrm{O}(\mathrm{s}).$
  • A
    $(A)$ only.
  • B
    $(B)$ Only.
  • ✓
    $(C)$ and $(D).$
  • D
    $(B), (C)$ and $(D).$
Answer
Correct option: C.
$(C)$ and $(D).$
Iodine is a non$-$ polar molecular solid iodine moleculas are held together by london force or dispersion force , this is soft and non$-$conductor fo electricity.
Water is a hydrogen bonded molecular solid in which $H$ and $O$ are held together by to non$-$ionic nature, they are not electrical conductor.
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MCQ 181 Mark
Schottky defect is observed in crystals when $.......$
  • A
    Some cations move from their lattice site to interstitial sites.
  • ✓
    Equal number of cations and anions are missing from the lattice.
  • C
    Some lattice sites are occupied by electrons.
  • D
    Some impurity is present in the lattice.
Answer
Correct option: B.
Equal number of cations and anions are missing from the lattice.
 
Defect
Definition
Type of solid
Effect of defect on density of substance
Structure fo crystal $($with defect$)$
Schottky defect A crystal is said to have Schottky defect if equal number of cations and anions are missing from their normal lattice site there by creating vacancies or holes.
Ionic solid
 Decreases
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MCQ 191 Mark
The lattice site in a pure crystal cannot be occupied by $.......$
  • A
    Molecule.
  • B
    Ion.
  • ✓
    Electron.
  • D
    Atom.
Answer
Correct option: C.
Electron.
Pure crystals have constituents i.e., atoms or molecules or ions as lattice points which are arranged in fixed stoichiometric ratio. Electron can occupy the lattice site only when there is imperfection in solid and not in a pure crystal.
Hence, existence of free electrons are not possible, it is possible on in case of imperfection in solid.
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MCQ 201 Mark
The edge lengths of the unit cells in terms of the radius of spheres constituting $\text{fcc, bcc}$ and simple cubic unit cell are respectively $.......$
  • ✓
    $2\sqrt{2\text{r}},\frac{4\text{r}}{\sqrt{3}},2\text{r}$
  • B
    $\frac{4\text{r}}{\sqrt{3}},2\sqrt{2\text{r}},2\text{r}$
  • C
    $2\text{r},2\sqrt{2\text{r}},\frac{4\text{r}}{\sqrt{3}},$
  • D
    $2\text{r},\frac{4\text{r}}{\sqrt{3}},2\sqrt{2\text{r}}$
Answer
Correct option: A.
$2\sqrt{2\text{r}},\frac{4\text{r}}{\sqrt{3}},2\text{r}$
Note: Distance between two atoms is always measured from their centres.
  1. If the crystal lattice consists of $\text{SCC},$ the atom which is present at the comers touch each other.
  1. In case of $\text{FCC},$ atom present at the comer and the centre of the face touch each other.
  1. In case of $\text{BCC}$ atom present at the corner and center of the body touch each other.

Edge lenght for different types of unit cells can be tabulated as
Type of unit cell
Edge LEnght
$\text{fcc}$
$2\sqrt{2\text{r}}$
$\text{bcc}$
$\frac{4}{\sqrt{3}}\text{r}$
$\text{scc}$
$2r$
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MCQ 211 Mark
Which of the following molecule has higher lattice energy?
  • A
    $\text{NaCl}.$
  • ✓
    $\mathrm{Mg}_1 \mathrm{N}_3$
  • C
    Both $(A)$ and $(B)$ have equal lattice energy.
  • D
    None of these
Answer
Correct option: B.
$\mathrm{Mg}_1 \mathrm{N}_3$
Lattice energy of a crystal is defined as the energy required to break an ionic crystal into its constituent ions in an isolated gaseous state. More ionic the compound is stronger will be its ionic bond and higher will be its lattice energy. In $\mathrm{MgN}_3$ the charge on the ionic species is greater than $\text{NaCl} .$ So, ionic interactions in $\mathrm{MgN}_3$ will be stronger.
So, lattice energy of $\mathrm{MgN}_3$ is greater than $\text{NaCl}$
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MCQ 221 Mark
$\text{ZnS}$ can be existing in the $......$ structure other than zing blende structure.
  • A
    $\text{Bcc}$
  • ✓
    Wurtzite
  • C
    Simple cubic
  • D
    Rock salt
Answer
Correct option: B.
Wurtzite
Wurtzite is a zinc iron sulfide mineral frequently encountered mineral form of sphalerite.
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MCQ 231 Mark
Crystal of sodium chloride belong to the $......$ system:
  • A
    Orthorhombic
  • ✓
    Cubic
  • C
    Trigonal
  • D
    Monoclinic
Answer
Correct option: B.
Cubic
In sodium chloride $(\text{NaCl}),$ the chloride ions are arranged in a cubic structure $($called as face centered cubic$)$ and sodium ions occupy octahedral voids between them. Each sodium ion is surrounded by $6$ chloride ions.
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MCQ 241 Mark
Packing efficiency of hcp structure is $.....:$
  • A
    $68\%$
  • B
    $52.4\%$
  • ✓
    $74\%$
  • D
    $82\%$
Answer
Correct option: C.
$74\%$
Both $\text{ccp}$ and $\text{hcp}$ are highly efficient lattice; in terms of packing. The packing efficiency of both types of close packed structure is $74\%,$ i.e. $74\%$ of the space in $\text{hcp}$ and $\text{ccp}$ is filled. The $\text{hcp}$ and $\text{ccp}$ structure are equally efficient; in terms of packing.
The packing efficiency of simple cubic lattice is $52.4\%.$ And the packing efficiency of body centered cubic lattice $(\text{bcc})$ is $68\%.$
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MCQ 251 Mark
Which of the following is not a crystalline solid?
  • A
    Common salt
  • B
    Sugar
  • C
    Iron
  • ✓
    Rubber
Answer
Correct option: D.
Rubber
Common salt, sugar and iron are crystalline solids whereas rubber is an amorphous solid as it does not have well developed perfectly ordered crystalline structure. Other amorphous solids include tar, glass, plastic, butter etc.
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MCQ 261 Mark
Diamond shows $.......$ lusture:
  • ✓
    Adamantine
  • B
    Resinous
  • C
    Pearly
  • D
    Translucent
Answer
Correct option: A.
Adamantine
Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. Adamantine minerals possess a superlative lustre, which is most notably seen in diamond. Such minerals are transparent or translucent, and have a high refractive index $($of $1.9$ or more$).$ Minerals with a true adamantine lustre are uncommon.
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MCQ 271 Mark
The close$-$packing sequence $\text{ABAB} ......$ represents:
  • A
    $SC$ packing
  • B
    $\text{FCC}$ packing
  • ✓
    Hexagonal packing
  • D
    $\text{BCC}$ packing
Answer
Correct option: C.
Hexagonal packing
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MCQ 291 Mark
Packing efficiency in a unit cell is never $100\%$ because constituent particles are assumed to be:
  • ✓
    Spheres
  • B
    Cuboid
  • C
    Cubes
  • D
    Conical
Answer
Correct option: A.
Spheres
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MCQ 301 Mark
In a crystal, atoms are located at the position of:
  • A
    Maximum potential energy
  • ✓
    Minimum potential energy
  • C
    Zero potential energy
  • D
    Infinite potential energy
Answer
Correct option: B.
Minimum potential energy
a crystal, atoms are located at the position of minimum potential energy.
As two atoms approach each other, the potential energy gradually decreases, reaches a minimum value and then sharply increases.
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MCQ 311 Mark
Absorption of photons by crystal:
  • A
    Has no effect on imperfection
  • ✓
    Produce atomic displacement leading to imperfections
  • C
    Decreases number of defects
  • D
    None of the above
Answer
Correct option: B.
Produce atomic displacement leading to imperfections
Absorption of photons by crystal produce atomic displacement leading to imperfections.
These imperfections are also called defects.
These are deviations from perfectly ordered arrangement.
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MCQ 321 Mark
Which one of the following is a pseudo solid?
  • A
    Calcium fluoride
  • ✓
    Glass
  • C
    Sodium chloride
  • D
    All of the above
Answer
Correct option: B.
Glass
Pseudo solid is a solid which possesses the property of liquids. Glass is a pseudo solid and in a very slowprocess, it flows like a liquid due to which the base of glass gets thicker than top.
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MCQ 331 Mark
Which of the following is a network solid?
  • ✓
    $\mathrm{SO}_2 ($Solid$).$
  • B
    $I_2$.
  • C
    Diamond.
  • D
    $\mathrm{H}_2 \mathrm{O} ($Ice$).$
Answer
Correct option: A.
$\mathrm{SO}_2 ($Solid$).$
Diamond is a three$-$dimensional network solid in which each carbon atom is tetrahedral bonded with four carbon atoms.
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MCQ 341 Mark
The incorrect statement among the following is:
  • ✓
    The fraction of total volume occupied by the atoms in a primitive cell is $0.48.$
  • B
    Molecular solids are generally volatile.
  • C
    The number of carbon atoms in an unit cell of diamond is $8.$
  • D
    The number of Bravais lattices in which a crystal can be categorized is $14.$
Answer
Correct option: A.
The fraction of total volume occupied by the atoms in a primitive cell is $0.48.$
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MCQ 351 Mark
Which of the following is an interstitial compound?
  • A
    $\mathrm{PdCl}_2$
  • B
    $\mathrm{NH}_3$
  • C
    $\mathrm{ZnO}$
  • ✓
    $\mathrm{TiH}$
Answer
Correct option: D.
$\mathrm{TiH}$
An interstitial compound is a compound that is formed when an atom with a small enough radius sits in an interstitial hole in a metal lattice. Examples of small atoms are boron, carbon and nitrogen. These compounds play an important role in industries.
Examples$:\ \mathrm{TiH}, \mathrm{Fe}_3 \mathrm{H}$ and $\mathrm{Mn}_4 \mathrm{N}$
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MCQ 361 Mark
Crystal structure of $\text{NaCl}:$
  • ✓
    Face centered cubic
  • B
    Body centered cubic
  • C
    Hexagonal
  • D
    Tetrahedral
Answer
Correct option: A.
Face centered cubic
$\text{NaCl}$ has a face$-$centred cubic unit cell. Chloride ions $($being larger in size$)$ form cubic close packing. They are present at the corners and at the centre of each face of the cube. Smaller sodium ions are present in all the octahedral holes.
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MCQ 371 Mark
Graphite is a good conductor of electricity due to the presence of $......$
  • A
    Lone pair of electrons.
  • ✓
    Free valence electrons.
  • C
    Cations.
  • D
    Anions.
Answer
Correct option: B.
Free valence electrons.
In graphite one carbon atom is attached to three other carbon atoms. One electron of carbon remains free. Due to this free valence electron graphite is an electrical conductor.
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MCQ 381 Mark
Beautiful crystals arise from various chemical substances. A single chemical can, sometimes, give rise to different crystals because of different:
  • A
    Angles of vision
  • ✓
    Arrangement of atoms in space
  • C
    Composition
  • D
    Weight of atoms
Answer
Correct option: B.
Arrangement of atoms in space
Different types of crystal system arised due to difference in the arrangement of atoms in the space.
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MCQ 391 Mark
Silver halides generally show:
  • A
    Schottky defect
  • B
    Frenkel defect
  • ✓
    both Frenkel and Schottky defects
  • D
    cation excess defect
Answer
Correct option: C.
both Frenkel and Schottky defects
Silver halides show both Frenkel and Schotkky defects. For Frenkel defect the reason is that there is size difference between the sizes of silver and halide.
Schottky defect is possible because silver halides are highly ionic.
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MCQ 401 Mark
The percentage of empty space in a body centred cubic arrangement is $.......$
  • A
    $74$
  • B
    $68$
  • ✓
    $32$
  • D
    $26$
Answer
Correct option: C.
$32$
Packing efficiency for $\text{bcc}$ arrangement is $68\%$ which represents total filled space in the unit cell. Hence, empty space in a body centered arrangement is $100 - 68 = 32\%.$
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MCQ 411 Mark
Graphite cannot be classified as $........$
  • A
    Conducting solid.
  • B
    Network solid.
  • C
    Covalent solid.
  • ✓
    ionic solid.
Answer
Correct option: D.
ionic solid.
Graphite is a covalent or Network solid, therefore it cannot be grouped as an ionic solid.
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MCQ 421 Mark
In which pair most efficient packing is present?
  • A
    $\text{hcp}$ and $\text{bcc}.$
  • ✓
    $\text{hcp}$ and $\text{ccp}.$
  • C
    $\text{bcc}$ and $\text{ccp}.$
  • D
    $\text{bcc}$ and simple cubic cell.
Answer
Correct option: B.
$\text{hcp}$ and $\text{ccp}.$
In $\text{hcp}$ and $\text{ccp}$ the packing efficiency is maximum $($i.e. $74\%),$ hence this pair of packing is considered as "most efficient packing".
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MCQ 431 Mark
$\mathrm{Na}_2 \mathrm{O}$ has:
  • A
    $\text{NaCl}$ structure
  • B
    $\text{ZnS}$ structure
  • C
    Fluorite structure
  • ✓
    Antifluorite structure
Answer
Correct option: D.
Antifluorite structure
$\mathrm{Na}_2 \mathrm{O}$ structure is antifluorite type structure in which $\mathrm{O}^{2-}$ ions forms $\text{ccp}\ ($cubic close packing$)$ and $\mathrm{Na}^{+}$ occupy all tetrahedral voids.
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MCQ 441 Mark
Which of the following statements is not true?
  • A
    Paramagnetic substances are weakly attracted by magnetic field.
  • ✓
    Ferromagnetic substances cannot be magnetised permanently.
  • C
    The domains in antiferromagnetic substances are oppositely oriented with respect to each other.
  • D
    Pairing of electrons cancels their magnetic moment in the diamagnetic substances.
Answer
Correct option: B.
Ferromagnetic substances cannot be magnetised permanently.
Ferromagnetic species are strongly attracted in the magnetic field and can be permanently magnetised. Hence, choice $(b)$ is the correct answer while other three choices are correct.
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MCQ 451 Mark
Which one is an amorphous solid?
  • A
    Diamond
  • B
    Graphite
  • C
    Common salt
  • ✓
    Glass
Answer
Correct option: D.
Glass
Glass is an amorphous solid. It is called psuedo solid. Diamond, graphite and common salt are crystalline solids.
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MCQ 461 Mark
Which of the following curves is in accordance with Freundlich adsorption isotherm?
 
  • ✓
  • B
  • C
  • D
Answer
Correct option: A.
$\frac{\text{x}}{\text{m}}=\text{kp}^\frac{1}{\text{n}}$
$\log\frac{\text{x}}{\text{m}}=\log\text{k}+\frac{1}{\text{n}}\log\text{p}$
Hence$, \log \Big(\frac{\text{x}}{\text{m}}\Big)$ versus $\log p$ is a straight line with a positive intercept.
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MCQ 471 Mark
Which of the following is not an amorphous substance?
  • ✓
    Copper
  • B
    Rubber
  • C
    Glass
  • D
    Polymers
Answer
Correct option: A.
Copper
The amorphous substance is defined as any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. As Rubber, Glass and Polymers of high molecular mass are examples of amorphous solids and Copper is not an amorphous substance.
Copper is an example of a crystalline solid.
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MCQ 481 Mark
Crystalline allotrope of silicon has:
  • ✓
    Diamond like structure
  • B
    Graphite like structure
  • C
    fullerene like structure
  • D
    $\mathrm{sp}^2$ hybridization
Answer
Correct option: A.
Diamond like structure
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MCQ 491 Mark
The correct order of the packing efficiency in different types of unit cells is $......$
  • ✓
    $\text{fcc < bcc <}$ simple cubic.
  • B
    $\text{fcc > bcc >}$ simple cubic.
  • C
    $\text{fcc < bcc >}$ simple cubic.
  • D
    $\text{bcc < fcc >}$ simple cubic.
Answer
Correct option: A.
$\text{fcc < bcc <}$ simple cubic.
 
Unit Cell
Packing Efficiancy
$\text{fcc}$ $74\%$
$\text{bcc}$ $68\%$
Simple Cubic
 $52.4$
This follows the order$:\ \text{fcc > bcc >}$ simple cubic.
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MCQ 501 Mark
A metallic crystal crystallizes into a lattice containing a sequence of layers $\text{ABABAB}....$ Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space ?
  • A
    $74\%$
  • ✓
    $26\%$
  • C
    $50\%$
  • D
    None of these
Answer
Correct option: B.
$26\%$
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M.C.Q (1 Marks) - Chemistry STD 12 Science Questions - Vidyadip