Chemistry

Solid State and Crystal Structures

198 Questions

Solid state chemistry focuses on the structural properties of crystalline solids. Questions cover Bravais lattices, unit cells, and close packed structures. This topic is essential for chemistry papers in UPSC and state PSC examinations.

Bravais lattice typesUnit cell calculationsClose packed structuresCrystal densityBragg's LawWurtzite structure

Solid State and Crystal Structures Questions

Multiple choice

Which of the following statements is/are not correct about halite structure?

  1. Cations occupy the lattice points of expanded fcc lattice and the anions occupy all the octahedral holes.
  2. The limiting radius ratio is in between 0.414 and 0.732.
  3. The coordination numbers of cation and anion are 4 and 8 respectively.
  4. The general formula of ionic compounds having halite structure is AB.

  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In halite or rock-salt structure, anions occupy the lattice points of expanded face centred cubic lattice and the cations occupy all the octahedral holes. The limiting radius ratio is in between 0.414 and 0.732. The co-ordination numbers for both cation and anion is 6:6. The general formula of ionic compounds having this structure is AB. Examples: NaCl, KCl, MgO, CaO etc.

Multiple choice

Which of the following statements is not correct regarding the bcc system?

  1. Packing efficiency of BCC lattice structure is 74%.
  2. HCP and BCC lattice structures have same packing efficiency.
  3. Coordination number of atoms in BCC crystal lattice is 8.

  1. Only 1

  2. Only 2

  3. Only 3

  4. 1 and 2

  5. 2 and 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Packing efficiency in HCP lattice is 74%. Packing efficiency of BCC lattice structure is 68%. HCP and BCC lattice structures have different packing efficiency. Thus, this option is correct.  

Multiple choice

Atoms of element B form hcp lattice and those of the element A occupy 2/3rd of tetrahedral voids. What is the formula of the compound formed by the elements A and B?

  1. A3B4

  2. A4B3

  3. A2B3

  4. A3B2

  5. AB
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The number of tetrahedral voids formed is equal to twice the number of atoms of element B and only 2/3rd of these are occupied by the atoms of element A. Hence, the ratio of the number of atoms of A and B is 2 × (2/3):1 or 4:3 and the formula of the compound is A4B3.

Multiple choice

In cubic closed pack structure of mixed oxides, the lattice is made up of oxide ions, one eighth of the octahedral voids are occupied by divalent ions (A2+), while one half of the octahedral voids are occupied by trivalent ions (B3+). The formula for the oxide is

  1. A3B2O4

  2. A2B2O4

  3. AB2O4

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  Let the number of oxides be = x So number of octahedral  voids = x And number of tetrahedral voids = 2x Number of A2+ ion = 2x/8 = x/4 Number of B3+ ions = x/2 A2+ : B3+ : O2- x/4: x/2: x 1:2:4 Hence the formula for the oxide is AB2O4

Multiple choice

In a laboratory, NaCl is made by burning Na in the atmosphere of Cl, which is yellow in colour. The yellow colour is due to the presence of

  1. electrons in the crystal lattice

  2. Na+ ions in the crystal lattice

  3. Cl- ions in the crystal lattice

  4. face-centred cubic crystal lattice

  5. gold in the crystal lattice
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a laboratory, sodium chloride is made by burning sodium in the atmosphere of chlorine, which is yellow in colour. The cause of yellow colour is the presence of electrons in the crystal lattice.

Multiple choice

Identify the incorrect statements. P. Pentaborane-11shows symmetrical square pyramidal geometry. Q. CsBr crystal has face centred cubic structure. R. MgAl2O4 and Fe3O4 are identical in crystal structure.

  1. P only

  2. Q only

  3. R only

  4. P, Q

  5. Q, R
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

P. Pentaborane-11 (B5H11) has an unsymmetrical square pyramidal geometry, in which five boron atoms occupy the five corners of a square pyramid. Q. The crystal of CsBr has body centred cubic structure. R. MgAl2O4 and Fe3O4 have spinel structures. Hence, statement P and Q both are incorrect.

Multiple choice

The allotrope of boron containing unit cell of twelve boron atoms is

  1. amorphous boron

  2. β-rhombohedral boron

  3. α-rhombohedral boron

  4. γ-boron
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

α-rhombohedral boron has a unit cell of twelve boron atoms. The structure consists of B12 icosahedra in which each boron atom has five nearest neighbors within the icosahedron. If the bonding were the conventional covalent type then each boron would have donated 5 electrons.