MDCAT Chemistry chapter 5: Chemistry · Solids MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
37 exam-style questions on Chemistry · Solids, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Which of these is a general property of solids?
A
they take the shape of any container they are put in
B
their particles can diffuse, but far more slowly than in liquids
C
they are easily squeezed into a much smaller volume
D
they flow slowly whenever a small force is applied to them
Show answer
Answer: B. Solids are rigid, keep their shape and are almost incompressible because their particles are closely packed in fixed positions; even so, particles do diffuse very slowly, so two metal blocks clamped together for years show a little mixing at the join. Taking the shape of the container and flowing are properties of fluids.
2. The coinage metals copper, silver and gold all crystallise in the
A
hexagonal system
B
cubic system
C
tetragonal system
D
monoclinic system
Show answer
Answer: B. Cu, Ag and Au have face-centred cubic lattices, so they belong to the cubic system (a = b = c, all angles 90°). The hexagonal system includes metals such as magnesium and zinc.
3. Some amorphous solids, such as glass and many plastics, contain tiny regions in which the particles are regularly arranged. These regions are called
A
crystallites
B
unit cells
C
lattice points
D
cleavage planes
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Answer: A. Small ordered regions inside an otherwise disordered amorphous solid are crystallites. A unit cell is the repeating unit of a complete crystal lattice, which an amorphous solid lacks.
4. In the body-centred cubic lattice of sodium (atoms at the corners and at the centre of each cube), what is the coordination number of each sodium atom, the number of nearest neighbours touching it?
A
4
B
6
C
8
D
12
Show answer
Answer: C. The atom at the centre of the cube touches the eight corner atoms, and as every atom is equivalent, each has 8 nearest neighbours. 12 is the coordination number in close-packed metals such as copper, and 6 that of a simple cubic lattice.
5. Magnesium (m.p. 650 °C) melts at a far higher temperature than sodium (m.p. 98 °C). The main reason is that each magnesium atom
A
shares its electrons in directional covalent bonds
B
is heavier, so its atoms vibrate less and leave the lattice less easily
C
has one more electron shell than a sodium atom
D
releases two valence electrons into the electron sea, not one
Show answer
Answer: D. Metallic bonding grows stronger with the number of valence electrons each atom contributes: Mg2+ ions in a sea of two electrons per atom are held more strongly than Na+ ions with one. Both metals are in Period 3, so neither has an extra shell, and metallic bonds are not directional.
6. Which substance is correctly matched with its crystal system?
A
graphite: cubic
B
barium sulphate: hexagonal
C
white tin: tetragonal
D
sodium chloride: orthorhombic
Show answer
Answer: C. White tin is tetragonal (a = b ≠ c, all angles 90°). Graphite is hexagonal (diamond is the cubic form of carbon), barium sulphate is orthorhombic and sodium chloride is cubic.
7. When heated, an amorphous solid such as glass differs from a crystalline solid in that it
A
melts sharply at one fixed temperature
B
softens over a range of temperatures
C
sublimes without ever melting
D
decomposes into its elements
Show answer
Answer: B. In an amorphous solid the forces between particles are not all the same, so they give way over a range of temperature and the solid softens gradually. A crystalline solid, with identical forces throughout its lattice, has a sharp melting point.
8. Rhombic sulphur and monoclinic sulphur can exist together in equilibrium at about 96 °C; below this temperature the rhombic form is the stable one, and above it the monoclinic form. This temperature is called the
A
transition temperature
B
melting point
C
critical temperature
D
sublimation temperature
Show answer
Answer: A. The temperature at which two crystalline forms of the same substance coexist in equilibrium is its transition temperature; grey and white tin, for example, interconvert at about 13 °C. At a melting point a solid is in equilibrium with its liquid, not with another solid form.
9. In the face-centred cubic unit cell of sodium chloride, Cl− ions occupy the 8 corners and the 6 face centres, and Na+ ions occupy the 12 edge centres and the body centre. How many formula units of NaCl belong to one unit cell?
A
1
B
4
C
8
D
14
Show answer
Answer: B. Cl−: 8 × 1/8 + 6 × 1/2 = 4; Na+: 12 × 1/4 + 1 = 4. So the cell holds four Na+ and four Cl− ions, which is four NaCl units; 8 counts ions instead of formula units, and 14 counts every Cl− site as a whole ion.
10. The seven crystal systems are distinguished from one another by
A
the number of particles in each unit cell
B
the kind of chemical bonding between the particles
C
the edge lengths and angles of the unit cell
D
the size of the particles in the lattice
Show answer
Answer: C. Each crystal system has its own pattern of unit cell edges (a, b, c) and angles (α, β, γ): for example cubic has a = b = c with all angles 90°, while tetragonal has a = b ≠ c with all angles 90°. Substances with quite different bonding can crystallise in the same system.
37, each with the answer and a short explanation, across 1 topics: Crystalline solids. Every chapter test draws ten of them, so you can take it many times.
Is the MDCAT Chemistry chapter 5 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
