Crystalline Solids

Crystalline Solids MDCAT MCQs with answers

40 past paper MCQs on Crystalline Solids, from the Solids unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

Read the notes first Practise the unit as a quiz

1.Some substances lack a definite heat of fusion. These substances are: (MDCAT 2020)

  1. isomorphs
  2. polymorphs
  3. amorphous solids
  4. crystalline solids
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Correct answer: (c) amorphous solids

Amorphous solids have no ordered lattice to break down at one temperature, so they soften over a range instead of melting sharply.

2.Whenever crystalline solids are broken they do so along definite planes known as: (MDCAT 2024)

  1. cleavage planes
  2. refractory planes
  3. sagittal planes
  4. coronal planes
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Correct answer: (a) cleavage planes

The regular lattice parts most easily along particular planes, called cleavage planes.

3.One of the following is NOT an example of an amorphous solid: (MDCAT 2024)

  1. plastic
  2. glass
  3. glucose
  4. rubber
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Correct answer: (c) glucose

Glucose is crystalline, with a sharp melting point; the other three have no long-range order.

4.Which one shows anisotropic behavior? (UHS MDCAT 2025)

  1. Wood
  2. Gemstone
  3. Coke
  4. Graphite
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Correct answer: (d) Graphite

Graphite conducts and cleaves along its layers but not across them, which is what anisotropy means.

5.Pick the crystalline solids: (UHS MDCAT 2025)

  1. Cement
  2. Ceramics
  3. Concrete
  4. Copper
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Correct answer: (b) Ceramics

Ceramics are crystalline; cement and concrete are amorphous mixtures.

6.Which of the following is not a crystalline solid? (SZABMU MDCAT 2025)

  1. KCl
  2. Fe metal
  3. Glass
  4. rhombic S
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Correct answer: (c) Glass

Glass is a supercooled liquid with no long range order, so it is amorphous.

7.Whenever the crystalline solids are broken they do so along definite planes known as: (UHS MDCAT 2024)

  1. Cleavage planes
  2. Refractory planes
  3. Sagittal planes
  4. Coronal planes
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Correct answer: (a) Cleavage planes

A crystal splits along its cleavage planes, where the lattice forces are weakest.

8.One of the following is NOT an example of amorphous solids (UHS MDCAT 2024)

  1. Plastic
  2. Glass
  3. Glucose
  4. Rubber
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Correct answer: (c) Glucose

Glucose forms proper crystals; plastic, glass and rubber have no long range order.

9.In graphite the carbon atoms are arranged in which of the following structure? (UHS MDCAT 2024)

  1. Rhombic
  2. Hexagonal
  3. Tetragonal
  4. Trigonal
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Correct answer: (b) Hexagonal

Graphite is built of flat sheets of carbon atoms in hexagonal rings.

10.The example of metallic solid is (KMU MDCAT 2024)

  1. B
  2. C
  3. Cu
  4. Si
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Correct answer: (c) Cu

Copper is a metal; boron, carbon and silicon here form covalent solids.

11.When a crystalline substance conducts current in one direction but not through other directions of the crystal, this property is (KMU MDCAT 2024)

  1. Allotropy
  2. Anisotropy
  3. Isomorphism
  4. Polymorphism
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Correct answer: (b) Anisotropy

A property that differs with the direction taken through the crystal is anisotropy.

12.Which of the following compound have any characteristic heat of fusion except? (NUMS MDCAT 2024)

  1. NaCl
  2. Aluminium oxide
  3. Iron oxide
  4. Silicates
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Correct answer: (d) Silicates

Silicates are amorphous, so they soften over a range instead of melting at a fixed point.

13.Q.82 Which type of solid is called as atomic solid? (UHS MDCAT 2023)

  1. Covalent solids
  2. Ionic solids
  3. Metallic solids
  4. Molecular solids
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Correct answer: (c) Metallic solids

A metal crystal is built of atoms in a sea of electrons, so it is called an atomic solid.

14.The molecules of iodine (I2) form the: (SZABMU MDCAT 2023)

  1. Molecular crystals
  2. Covalent crystals
  3. Ionic crystals
  4. Metallic crystals
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Correct answer: (a) Molecular crystals

Iodine molecules are held in the lattice by weak dispersion forces, so the crystal is molecular.

15.The type of bonding in Zinc is: (SZABMU MDCAT 2023)

  1. Ionic
  2. Covalent
  3. Dative
  4. Metallic
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Correct answer: (d) Metallic

Zinc is a metal, its atoms held by a sea of delocalized electrons.

16.Thermal conductivity of metals is due to: (NUMS MDCAT 2023)

  1. Layered structure of metals
  2. Freely moving electrons
  3. Loosely held metal atoms
  4. Vibrational movement of metals
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Correct answer: (b) Freely moving electrons

The delocalized electrons carry the energy quickly through the metal.

17.Which of the following substance is malleable and ductile? (NUMS MDCAT 2023)

  1. Sodium chloride
  2. Copper sulphate
  3. Mercury
  4. Aluminum
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Correct answer: (d) Aluminum

A metal can be beaten into sheets and drawn into wire because its layers slide without breaking the bonding.

18.In anisotropic crystals which property do not change with the change in direction of crystalline structure? (UHS MDCAT 2023)

  1. Electrical conductance
  2. Thermal conductance
  3. Molar mass
  4. Refractive index
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Correct answer: (c) Molar mass

Anisotropy is about properties measured along a direction; the molar mass has no direction.

19.In metals, why electric conductivity decreases with the increase of temperature? (UHS MDCAT 2023)

  1. Because electron movement decrease with the increase of temperature
  2. Because metal ions oscillations hinder electron movement
  3. Because electron direction changes at high temperature
  4. Because they pass heat current through collision of electrons
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Correct answer: (b) Because metal ions oscillations hinder electron movement

Heating makes the ions vibrate more widely, and the electrons are scattered by them.

20.The solid which is hardest of all types is _____? (PMC MDCAT 2022)

  1. Covalent solids
  2. Molecular solids
  3. Ionic solids
  4. Metallic solids
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Correct answer: (a) Covalent solids

A covalent network such as diamond is bonded right through, so it is the hardest kind of solid.

21.Which of the following properties of isomorphs is NOT true? (PMC MDCAT 2022)

  1. lsomorphs can make homogeneous mixtures together
  2. Have different physical properties
  3. Have same atoms
  4. Have same ratio of atoms
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Correct answer: (c) Have same atoms

Isomorphs have the same crystal shape and the same ratio of atoms, but the atoms themselves differ.

22.Polymorphs have same (PMC MDCAT 2022)

  1. Chemical Properties
  2. Melting points
  3. Structures
  4. boiling points
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Correct answer: (a) Chemical Properties

Polymorphs are the same substance in different crystal forms, so their chemistry is the same.

23.The repetition of faces, angles and edges of a crystal, when it is rotated to 360 degree angle is called: (PMC MDCAT 2022)

  1. Habit of crystal
  2. Isomorphism
  3. Symmetry
  4. Polymorphism
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Correct answer: (c) Symmetry

The repetition of faces and edges on turning is the symmetry of the crystal.

24.Which of the following crystal has highest density? (PMC MDCAT 2022)

  1. Iodine
  2. Graphite
  3. Ice
  4. Sodium Chloride
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Correct answer: (a) Iodine

Iodine is much the heaviest of these for its volume, so its crystal is the densest.

25.The properties which depends upon the direction are called: (PMC MDCAT 2022)

  1. Isotropic properties
  2. Anisotropic properties
  3. Additive properties
  4. Colligative properties
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Correct answer: (b) Anisotropic properties

A property that differs with the direction taken through the crystal is anisotropic.

26.Which of the following solid has indefinite heat of fusion? (PMC MDCAT 2022)

  1. Crystalline solids
  2. Pure solids
  3. True solids
  4. Amorphous solids
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Correct answer: (d) Amorphous solids

An amorphous solid has no fixed melting point, so it has no definite heat of fusion.

27.The following are anisotropic properties except: (PMC MDCAT 2022)

  1. Refractive Index
  2. Thermal conductivtiy
  3. Electrical conductivity
  4. Melting points
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Correct answer: (d) Melting points

A melting point is one number for the whole crystal, so it cannot vary with direction.

28.Malleability is a property of metals which means_____? (PMC MDCAT 2022)

  1. Drawn into wires
  2. Converted into sheets
  3. Drawn into wires and converted into sheets
  4. Breakable
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Correct answer: (b) Converted into sheets

Malleable means it can be beaten into sheets; ductile means it can be drawn into wire.

29.Which solids are also called as atomic solids? (PMC MDCAT 2022)

  1. Ionic solids
  2. Covalent solids
  3. Molecular solids
  4. Metallic solids
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Correct answer: (b) Covalent solids

A covalent network such as diamond is one giant molecule of atoms, so it is called an atomic solid.

30.Who proposed valence bond theory for metals? (PMC MDCAT 2022)

  1. Loren
  2. Drudge
  3. L.Pauling
  4. Maxwell
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Correct answer: (c) L.Pauling

Pauling put forward the valence bond account of metallic bonding.

31.Which of the following Is not true about Polymorphs? (PMC MDCAT 2022)

  1. Have same chemical properties
  2. lnterconvertible
  3. Have same formula unlt
  4. Have different formula unit
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Correct answer: (d) Have different formula unit

Polymorphs are the same compound in different crystal forms, so their formula unit is the same.

32.A solid compounds exists is more than one crystalline form, this phenomenon is called (PMC MDCAT 2022)

  1. Allotropy
  2. Isomorphism
  3. Polymorphism
  4. Isomerism
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Correct answer: (c) Polymorphism

One compound crystallizing in more than one form is polymorphism.

33.Which of the following solids shows the phenomenal of Isomorphism? (PMC MDCAT 2022)

  1. Molecular Solids
  2. Covalent solids
  3. Ionic solids
  4. Metallic solids
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Correct answer: (c) Ionic solids

Ionic solids of similar formula and ion size crystallize in the same form, which is isomorphism.

34.Nature of diamond as solid is: (NUMS MDCAT 2022)

  1. Covalent
  2. Ionic
  3. Molecular
  4. Metallic
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Correct answer: (a) Covalent

Diamond is a covalent network of carbon atoms bonded right through the crystal.

35.Which one of the following is as light as a feather and as strong as iron? (NUMS MDCAT 2022)

  1. Graphite
  2. Graphene
  3. Mercury
  4. Diamond
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Correct answer: (b) Graphene

Graphene is a single sheet of graphite, almost weightless and stronger than steel.

36.The temperature at which one crystalline form changes to another is called ____ temperature. (PMC Practice 2021)

  1. Critical
  2. Absolute
  3. Transition
  4. None of these options is correct
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Correct answer: (c) Transition

The temperature at which one crystalline form changes into another is the transition temperature.

37.Graphite has a structural similarity with: (PMC Practice 2021)

  1. B2H6
  2. B4C
  3. B
  4. BN
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Correct answer: (d) BN

Boron nitride has the same layered hexagonal structure as graphite.

38.Allotropes are of same? (PMC Practice 2021)

  1. Compounds
  2. Molecules
  3. Ions
  4. Elements
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Correct answer: (d) Elements

Allotropes are different forms of the same element.

39.Which of the following substances has giant covalent structure? (PMC MDCAT 2020)

  1. Iodine crystal
  2. Solid CO2
  3. Silica
  4. White phosphorus
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Correct answer: (c) Silica

Silica is bonded covalently right through the crystal.

40.Electrical conductivity of graphite is greater in one direction that in other due to (UHS MDCAT 2016)

  1. Isomorphism
  2. Cleavage plane
  3. Anisotropy
  4. Symmetry
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Correct answer: (c) Anisotropy

Graphite conducts along its layers but not across them, which is anisotropy.

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