Chemistry

Solid State and Crystal Structures

151 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

A molecule of CsCl in the solid-state has

  1. Face-centered cubic structure

  2. Body-centered cubic structure

  3. Simple cubic structure

  4. Close-packed hexagonal structure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In solid CsCl (cesium chloride), the structure is body-centered cubic (BCC). In this arrangement, Cs+ ions occupy the corners of the cube and one Cl- ion sits at the body center (or vice versa). This differs from the simple cubic, face-centered cubic, or hexagonal close-packed structures. Each ion is surrounded by eight ions of the opposite type, giving it a coordination number of 8.

Multiple choice

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

  1. P3Q4

  2. P4Q3

  3. P2Q3

  4. P3Q2

  5. PQ
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 Q and only 2 / 3rd of these are occupied by the atoms of element P. Hence, the ratio of the number of atoms of P and Q is 2 × (2 / 3) : 1 or 4 : 3 and the formula of the compound is P4Q3.

Multiple choice

An element has a body-centred cubic (BCC) structure with a cell edge of 210 pm. The density of the element is 4.2 g/cm3. Number of atoms present in 210 g of the element is

  1. 5.03 x 1024

  2. 10.06 ×1024

  3. 20.12 × 1024

  4. 30.18 ×1024

  5. 40.24 ×1024
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Volume of the unit cell = (210 pm)3= (210 ×10-12 m)3 = (210 × 10-10 cm)3 = 9.94 × 10-24 cm3 Volume of 208 g of the element = mass / density = 210 g / 4.2 g cm-3 = 50 cm3 Number of unit cells in this volume = 50 cm3 / 9.94 x 10-24 cm3 = 5.03 x 1024 Since each bcc cubic unit cell contains 2 atoms, so the total number of atoms in 210 g of the element = 2 (atoms / unit cell) × 5.03 x 1024 unit cells = 10.06×1024 atoms

Multiple choice

Which of the following statements are incorrect regarding rock-salt structure? P. Cations occupy the lattice points of expanded face centred cubic lattice and the anions occupy all the octahedral holes. Q. The limiting radius ratio is in between 0.414 and 0.732. R. The coordination numbers of cation and anion are 4 and 8 respectively. S. The general formula of ionic compounds having rock-salt structure is AB. Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. R and S
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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.