# Ch-3: Tutorial Crystallographic Directions &amp; Crystallographic Plans

```Ch-3: Tutorial
Crystallographic Directions &amp; Crystallographic Plans
1- The number of atoms present in the unit cell of HCP structure is:
(1) 2
(2) 4
(3) 6
(4) 12
2- The unit cell has a = 5 &Aring;, b = 8 &Aring;, c = 3 &Aring;, α = 90&deg;, β= 65&deg; and γ =
54&deg;. The space lattice for this unit cell is:
(1) monoclinic (2) rhombohedral (3) triclinic (4) orthorhombic
3- The lattice constant of a BCC unit cell with atomic radius of 1.24 &Aring; is:
(1) 1.432 &Aring;
(2) 2.864 &Aring; (3) 1.754 &Aring; (4) 1.432 &Aring;
4- The correct order of coordination number in BCC, FCC and HCP unit
cells is:
(1) 12, 8, 6
(2) 8, 12, 12
(3) 6, 8, 12
(4) 12, 8, 24
5- The Miller indices of the plane parallel to Y and Z axes are:
(1) (0 0 1)
(2) (1 1 1) (3)
(0 1 0)
(4) (1 0 0)
6- A plane in a unit cell is described by its Miller indices (632).The plane
intersects x, y, z respectively at points whose distances from origin are:
(1) 6, 3 and 2 units
(2) 1/3, 2/3 and 1 units
(3) 1/3, 1/2 and 1/1 units
(4) 1/6, 1/3 and 1/2 units
Q: What are the three relatively simple crystal structures in which most
common metals exist?
Ans. FCC, BCC and HCP.
```