Questions on Crystal Systems
20 Multiple-Choice Questions on Crystal Systems
1. Which of the following is NOT one of the seven crystal systems?
A) Cubic
B) Tetragonal
C) Orthorhombic
D) Hexagonal
E) Molecular
2. How many crystal systems are there in total?
A) 5
B) 6
C) 7
D) 8
E) 9
3. Which crystal system is characterized by three axes of equal length intersecting at 90°?
A) Monoclinic
B) Cubic
C) Orthorhombic
D) Triclinic
E) Tetragonal
4. In the tetragonal crystal system, the axes lengths are:
A) a = b ≠ c, all at 90°
B) a ≠ b ≠ c, all at 90°
C) a = b = c, all at 90°
D) a ≠ b ≠ c, none at 90°
E) a = b = c, none at 90°
5. The monoclinic crystal system has how many axes intersecting at 90°?
A) Three
B) Two
C) One
D) Zero
E) None
6. Which crystal system has the least symmetry?
A) Cubic
B) Hexagonal
C) Triclinic
D) Orthorhombic
E) Tetragonal
7. What is the angle arrangement in a hexagonal crystal system?
A) All angles 90°
B) Two angles 90°, one 120°
C) All angles 120°
D) Angles less than 90°
E) None of the angles are 90°
8. Which of the following crystal systems has axes of unequal lengths and all angles at 90°?
A) Cubic
B) Orthorhombic
C) Hexagonal
D) Monoclinic
E) Triclinic
9. Which crystal system is defined by three unequal axes with two angles at 90° and one angle not 90°?
A) Orthorhombic
B) Monoclinic
C) Triclinic
D) Tetragonal
E) Cubic
10. The rhombohedral system is a subset of which crystal system?
A) Tetragonal
B) Hexagonal
C) Cubic
D) Monoclinic
E) Orthorhombic
11. What is the main characteristic of the triclinic system?
A) All axes equal, all angles 90°
B) Two axes equal, all angles 90°
C) No axes equal, no angles 90°
D) Three axes equal, two angles 120°
E) All axes equal, two angles 120°
12. Which crystal system commonly forms salt crystals (like NaCl)?
A) Orthorhombic
B) Cubic
C) Monoclinic
D) Tetragonal
E) Hexagonal
13. Which crystal system has two axes equal and one different, with all angles at 90°?
A) Cubic
B) Tetragonal
C) Orthorhombic
D) Hexagonal
E) Triclinic
14. What distinguishes the hexagonal crystal system from the cubic system?
A) Cubic has three equal axes at 90°, hexagonal has two equal axes at 120°
B) Hexagonal has all axes equal at 90°
C) Cubic has unequal axes at 120°
D) Hexagonal has all axes equal at 90°
E) Cubic has two equal axes at 120°
15. Which crystal system has three axes of unequal length, and one angle not 90°?
A) Orthorhombic
B) Monoclinic
C) Triclinic
D) Tetragonal
E) Cubic
16. Quartz is commonly found in which crystal system?
A) Cubic
B) Hexagonal
C) Monoclinic
D) Orthorhombic
E) Triclinic
17. The unit cell in a cubic crystal system is typically:
A) Hexagon
B) Cube
C) Rectangle
D) Rhombus
E) Trapezoid
18. Which crystal system has one axis perpendicular to the other two, which are inclined?
A) Orthorhombic
B) Tetragonal
C) Monoclinic
D) Triclinic
E) Hexagonal
19. Which crystal system has lattice parameters a = b ≠ c and α = β = γ = 90°?
A) Cubic
B) Tetragonal
C) Orthorhombic
D) Monoclinic
E) Triclinic
20. Which crystal system is least likely to have symmetry operations like mirror planes or rotational axes?
A) Cubic
B) Triclinic
C) Hexagonal
D) Orthorhombic
E) Tetragonal
Answers and Explanations
1. E – Molecular is not a crystal system.
2. C – There are 7 crystal systems.
3. B – Cubic system has three equal axes at 90°.
4. A – Tetragonal has two equal axes (a = b) and a different third axis (c), all angles 90°.
5. B – Monoclinic has two axes at 90°, one angle not 90°.
6. C – Triclinic has the least symmetry.
7. B – Hexagonal system has two angles at 90°, and one at 120°.
8. B – Orthorhombic has three unequal axes, all 90°.
9. B – Monoclinic has three unequal axes with two angles 90°, one not 90°.
10. B – Rhombohedral is part of the hexagonal crystal family.
11. C – Triclinic has no equal axes and no angles at 90°.
12. B – Salt (NaCl) forms cubic crystals.
13. B – Tetragonal has two equal axes and one different, all angles 90°.
14. A – Cubic has three equal axes at 90°, hexagonal has two equal axes at 120°.
15. B – Monoclinic has this property.
16. B – Quartz crystallizes in the hexagonal system.
17. B – The cubic unit cell is a cube.
18. C – Monoclinic has one axis perpendicular, others inclined.
19. B – Tetragonal system fits this description.
20. B – Triclinic has minimal symmetry.
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