Top 10 Question for Board Exam - 01
Chapter - Solid State
1. “Crystalline solids are anisotropic in nature.” What does this statement mean?
2. Defne primitive unit cells.
3. How many atoms per unit cell (Z) are present in scc, bcc and fcc unit cell?
4. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 1/3rd of tetrahedral voids?
5. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 2/3rd of octahedral voids?
6. What is the coordination number of each type of ions in a rock-salt type crystal structure?
7. Express the relationship between atomic radius (r) and the edge length (a) in the scc, bcc and fcc unit cell.
8. Aluminium crystallises in a fcc structure. Atomic radius of the metal is 125 pm. What
is the length of the side of the unit cell of the metal?
9. Chromium metal crystallises in a body centred cubic lattice. The length of the unit cell edge is found to be 287 pm. Calculate the atomic radius of chromium.
10. The edge of the face-centred cubic unit cell of aluminium is 404 pm. Calculate the radius of aluminium atom. Answers - 1. Crystalline solids are anisotropic in nature because of different arrangements of particles in different directions. Some of their physical properties like electrical conductivity, refractive index, etc., shows different values in different directions in the same crystals.
2. A unit cell in which constituent particles (lattice points) are present only at the corner positions is called primitive or simple unit cell.
3. 1, 2 and 4, respectively.
6. 6 and 6
7. For scc - a = 2r
for bcc - r = root 3a/4
for fcc - r = a/2 root 2
8. a = 354 pm
9. r = 124.27 pm
10. r = 142.814 pm