Solids

Solids MDCAT MCQs with answers

69 past paper MCQs from Chemistry unit 5, Solids, across 5 topics. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

Practise as a quiz

Crystalline Solids

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.

All 40 Crystalline Solids MCQs → Crystalline Solids notes →

Crystal Lattice

4.The smallest block which carries the whole information about a crystal structure is called the: (MDCAT 2022)

  1. cell
  2. unit cell
  3. crystal lattice
  4. crystal unit
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Correct answer: (b) unit cell

Repeating the unit cell in three dimensions builds the whole lattice.

5.In graphite the carbon atoms are arranged in which of the following structures? (MDCAT 2024)

  1. rhombic
  2. hexagonal
  3. tetragonal
  4. trigonal
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Correct answer: (b) hexagonal

Each layer of graphite is a sheet of hexagons of $sp^2$ carbon atoms.

6.In a unit cell of a crystal lattice the angle β is between faces: (UHS MDCAT 2025)

  1. a and b
  2. b and c
  3. c and a
  4. not specified
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Correct answer: (c) c and a

By convention $\alpha$ lies between b and c, $\beta$ between c and a, and $\gamma$ between a and b.

All 14 Crystal Lattice MCQs → Crystal Lattice notes →

Factors Affecting the Shape of Ionic Crystals

7.Predict the shape of CsCl having radius ratio of 0.93: (NUMS MDCAT 2024)

  1. Tetrahedral
  2. Octahedral
  3. Body centered cubic
  4. Hexagonal
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Correct answer: (c) Body centered cubic

A radius ratio above $0.732$ gives eight-fold coordination, the caesium chloride body centred structure.

Lattice Energy

8.All of the following steps are used to calculate the lattice energy in the Born-Haber cycle EXCEPT: (MDCAT 2024)

  1. atomizing the metal
  2. ionizing the metal
  3. deionizing the metal
  4. ionizing the non-metal
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Correct answer: (c) deionizing the metal

The cycle atomizes and ionizes; there is no step that returns an ion to its atom.

9.The factor that affects the lattice energy is: (NUMS MDCAT 2025)

  1. Charge to size ratio
  2. Shielding effect
  3. Crystal structure
  4. Atomic radius
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Correct answer: (a) Charge to size ratio

Lattice energy rises with the charge on the ions and falls with their size.

10.The ionic compound among the following with the highest lattice energy is: (SIBA MDCAT 2025)

  1. LiF
  2. NaCl
  3. KCl
  4. CsI
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Correct answer: (a) LiF

Lattice energy is greatest for the smallest ions, and lithium fluoride has the smallest pair here.

All 13 Lattice Energy MCQs → Lattice Energy notes →

Ionic and Molecular Crystals Compared

11.Most molecular crystals melt below: (NUMS MDCAT 2025)

  1. 200°C
  2. 280°C
  3. 330°C
  4. 480°C
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Correct answer: (a) 200°C

Molecular crystals are held by weak intermolecular forces, so they melt low, mostly under $200^{\circ}\mathrm{C}$.

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