1. What is a primitive unit cell?
A.
The smallest unit cell containing lattice points only at its corners
B.
A unit cell containing lattice points at all face centres
C.
A unit cell containing lattice points at the body centre
D.
A unit cell containing lattice points along all edges
Correct Answer:
The smallest unit cell containing lattice points only at its corners
Explanation:
A primitive unit cell is the smallest repeating unit of a crystal lattice and has lattice points only at its corners.
2. How many lattice points are present in a primitive unit cell?
A.
One
B.
Two
C.
Four
D.
Eight
Correct Answer:
One
Explanation:
Each of the eight corner lattice points contributes one-eighth to a unit cell, so the total contribution is 8 × 1/8 = 1 lattice point.
3. In a primitive unit cell, where are the lattice points located?
A.
Only at the corners
B.
Only at the face centres
C.
Only at the body centre
D.
At the corners and face centres
Correct Answer:
Only at the corners
Explanation:
The defining feature of a primitive unit cell is that its lattice points occur only at the corners.
4. What fraction of a corner lattice point belongs to one unit cell?
A.
1/8
B.
1/2
C.
1/4
D.
1
Correct Answer:
1/8
Explanation:
A corner lattice point is shared equally by eight adjoining unit cells, so each unit cell contains one-eighth of it.
5. A primitive unit cell has eight corner lattice points. What is their total contribution to the unit cell?
A.
One lattice point
B.
Two lattice points
C.
Four lattice points
D.
Eight lattice points
Correct Answer:
One lattice point
Explanation:
Each corner contributes 1/8, giving a total contribution of 8 × 1/8 = 1 lattice point.
6. Which type of lattice cell is represented by a simple cubic cell?
A.
Primitive unit cell
B.
Face-centred unit cell
C.
Body-centred unit cell
D.
Base-centred unit cell
Correct Answer:
Primitive unit cell
Explanation:
A simple cubic cell has lattice points only at its eight corners, so it is a primitive unit cell.
7. If a unit cell contains no lattice point at its faces or body centre, it is most likely a:
A.
Primitive unit cell
B.
Face-centred unit cell
C.
Body-centred unit cell
D.
Base-centred unit cell
Correct Answer:
Primitive unit cell
Explanation:
A primitive unit cell contains lattice points only at the corners and has no additional lattice points on faces or inside the cell.
8. What is the main characteristic of a primitive unit cell compared with other unit cells?
A.
It contains the minimum possible number of lattice points
B.
It always contains a lattice point at the body centre
C.
It always contains lattice points at the face centres
D.
It contains the maximum possible number of lattice points
Correct Answer:
It contains the minimum possible number of lattice points
Explanation:
A primitive unit cell contains only one lattice point in total, which is the minimum required to generate the lattice by repetition.
9. What is the total number of lattice points contributed by the corners of any primitive unit cell?
A.
1
B.
3
C.
6
D.
8
Correct Answer:
1
Explanation:
The eight corner points each contribute one-eighth, so together they contribute one lattice point.
10. Which statement about a primitive unit cell is correct?
A.
It has one lattice point per unit cell after counting shared corners
B.
It has four lattice points per unit cell after counting shared corners
C.
It has six lattice points per unit cell after counting shared corners
D.
It has eight lattice points per unit cell after counting shared corners
Correct Answer:
It has one lattice point per unit cell after counting shared corners
Explanation:
Although a primitive unit cell has eight visible corner points, each is shared by eight cells, giving one lattice point in total.
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