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 imperfections in solids solid state the solid state chemistry

A strong current of trivalent gaseous boron passed through a germanium crystal decreases the density of the crystal due to part replacement of germanium by boron and due to interstitial vacancies created by missing Ge atoms. In one such experiment, one gram of germanium is taken and the boron atoms are found to be $150$ ppm by weight when the density of the Ge crystal decreases by $4\%$. Calculate the percentage of missing vacancies due to germanium which are filled up by boron atoms. Atomic weight of Ge $= 72.6$ amu and $B = 11$ amu.

  1. $2.4\, \%$
  2. $1.2\, \%$
  3. $6.6\, \%$

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As given,
$1$ g Germanium $\equiv  150$ ppm of Boron $=1.5 \times 10^{-4}$ g of Boron
$4\%$ decrease in density of Ge occurs in one experiment due to replacement of Ge by B.

The weight becomes $0.96$ g (Ge + B).
Hence, $0.04$ g is missing.
$0.04$ missing means $(0.04-0.00015)$ g Ge missing $= \dfrac{(0.04-0.00015)}{72.61}$ moles
Ge missing $=$ $5.488\times 10^{-4}$ moles
Boron replaced $=$ $1.5\times 10^{-4} g = \dfrac{(1.5\times 10^{-4})}{10}$ moles
Equivalently replaced $= \dfrac 34\times $ $\dfrac{1.5\times 10^{-4}}{10}$ moles of Ge ( Valency of B is $3$ and Ge is $4$.)
$=0.1125\times 10^{-4}$ moles of Ge
Percentage of missing vacancies filled by B atoms $=\dfrac {0.1125\times 100}{5.488}$ $=2.05\%$

Multiple choice imperfections in solids solid state the solid state chemistry

The pink colour of lithium chloride crystal is due to:

  1. frenkel defect

  2. metal excess defect

  3. metal deficiency defect

  4. impurity defect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$LiCl$ has non-stochiometric metal excess defect due to anion vacancies. The negative ions $(Cl^-)$ are missing from their lattice sites leaving the holes in which electrons are entrapped so that electrical neutrality is maintained.

When $LiCl$ is heated, $Li$ atoms gets deposited on the surface of the crystal. The $Cl^-$ ions diffuse into the surface and combine with $Li$ atoms to give $LiCl$. This is so because of loss of electrons by $Li$ atoms to form $Li^+$. The released electrons diffuse excess into crystal and occupy anionic sites. As a result, there is an excess of $Li$. The anionic sites occupied by unpaired electrons are F-centers which imparts a pink color to $LiCl$ crystals. The color is observed as a result of excitation of these electrons when they absorb energy from visible light falling on crystals.

Multiple choice chemistry substances in the surroundings - their states and properties measurement of density properties of substances fundamental and derived units

If the mass of a body is $12.1  g$ and the density is $2.2  {g}/{cc}$, its volume is

  1. $5.5 {cm}^{3}$
  2. $8 cc$
  3. $11 cc$
  4. $55 cc$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 Density = $\dfrac {mass}{volume}$ 


 so volume =$\dfrac{mass}{density}$

hence volume =$\dfrac{12.1}{2.2} =5.5cc$

hence option (A) is correct

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

The distance between two consecutive atoms of the crystal lattice is $1.227\overset {\circ}{A}$. The maximum order of diffraction of electrons accelerated through $10^{4}$ volt will be:

  1. $10$
  2. $\dfrac {1}{10}$
  3. $100$
  4. $\dfrac {1}{100}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The de Broglie wavelength lambda = h / sqrt(2 * m * e * V). For V = 10^4 V, lambda is approx 0.1227 Angstroms. Bragg's law is 2 * d * sin(theta) = n * lambda. For maximum order n, sin(theta) = 1, so n = 2 * d / lambda = 2 * 1.227 / 0.1227 = 20. The calculation suggests 20, but 10 is the closest option.

Multiple choice

The space lattice of graphite is

  1. Cubic

  2. Tetragonal

  3. Rhombic

  4. Hexagonal
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Graphite consists of layers of carbon atoms arranged in a hexagonal pattern, which defines its hexagonal crystal system.

Multiple choice

Which of the following will have deficiency defect?

  1. NaCI

  2. FeO

  3. KCI

  4. ZnO
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

FeO (Ferrous oxide) is a classic example of a metal-deficient defect, where the ratio of iron to oxygen is less than 1:1 due to the presence of Fe(3+) ions replacing some Fe(2+) ions to maintain electrical neutrality.

Multiple choice

The Coordination no. of Y will be in the XY types of Crystal:

  1. 6

  2. 8

  3. 12

  4. 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In XY-type crystals (assuming AB-type like NaCl structure), if X has coordination number 6, then Y also has coordination number 6 due to the symmetrical nature of the structure. In NaCl-type crystals, each Na+ touches 6 Cl- and each Cl- touches 6 Na+.

Multiple choice

NaCl typecrystal (with coordination no.6 :6) can be converted into CsCl type crystal (with coordination no.8 :8)by apply

  1. High temperature

  2. High pressure

  3. High temperature and high pressure

  4. Low temperature and low pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Increasing pressure forces ions closer together, which favors a structure with a higher coordination number to maximize packing efficiency. Thus, NaCl (CN 6) converts to CsCl (CN 8) under high pressure.

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

In an ionic solid, ${B}^{x-}$ ions constitute a ccp lattice, if ${A}^{y+}$ ion occupy $25$% of the tetrahedral voids, the possible ions in the solid are:

  1. ${A}^{+}$ and ${B}^{-}$
  2. ${A}^{2+}$ and ${B}^{4-}$
  3. ${A}^{2+}$ and ${B}^{-}$
  4. ${A}^{4+}$ and ${B}^{-}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the number of B ions be N. The number of tetrahedral voids is 2N. A ions occupy 25% of 2N, which is 0.5N. The ratio A:B is 0.5:1, or 1:2. To maintain charge neutrality, if B is -1, A must be +2. Thus, A is +2 and B is -1.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

The lattice of a covalent crystal is composed of :

  1. atoms

  2. molecules

  3. ions

  4. compounds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A covalent network crystal consists of atoms at the lattice points of the crystal, with each atom being covalently bonded to its nearest neighbour atoms.


The covalently bonded network is three-dimensional and contains a very large number of atoms.

Examples of these crystals include graphite and diamond.
In these crystals, the atoms form covalent bonds with one another.