Tag: solid state

Quizzes (4) Questions (214)

Questions Related to solid state

Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following defects decrease the density?

  1. Interstitial defect

  2. Vacancy defect

  3. Frenkel defect

  4. Schottky defect
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

Vacancy and Schottky defect which lead to decrease the density both are the types of a stoichiometric defect. In case of Frenkel defect and interstitial defect, there is no change in density of substance.

Multiple choice imperfections in solids solid state the solid state chemistry

Frenkel defect is also known as

  1. stoichiometric defect

  2. dislocation defect

  3. impurity defect

  4. non-stoichiometric defect
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

(a, b) In Frenkel defect, dislocation of cations takes place and there is no change in stoichiometry of the crystal.

Multiple choice imperfections in solids solid state the solid state chemistry

Iron (II) oxide is written as $\overline{FeO}$. What does it mean?

  1. Fully pure

  2. Impure
  3. Ratio of $Fe$ and $O $ is 1:1

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

Impurity defects are foreign atoms that replace some  of the atoms making up the solid or that squeeze into the interstices; they are important in the electrical behaviour of semiconductors, which are materials used in computer chips and other electronic devices.

An example of interstitial impurity  atoms is the carbon atoms that are added to iron to make steel.

Multiple choice imperfections in solids solid state the solid state chemistry

Formula of metal oxide with metal deficiency defect in its crystal is $A _{0.8}O$. The crystal contains $A^{2+}$ and $A^{3+}$ ions. The fraction of metal existing as $A^{2+}$ ions in the crystal is

  1. $0.96$
  2. $0.04$
  3. $0.50$
  4. $0.31$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Solution:- (C) $0.50$

Fiormula is ${A} _{0.8}O$
So the ratio of $A : O = 80 : 100$
Thus, if there are $100$ atoms of oxygen then $80$ atoms of $A$.
Let $x$ be the no. of atopms of ${A}^{+2}$.
No. of atoms of ${A}^{+3} = 80 - x$
Charge on $A \; =$ Charge on $O$
Since oxygen has charge $-2$.
Therefore,
$2x + 3 \left( 80 - x \right) = 2 \times 100$
$2x + 240 - 3x = 200$
$\Rightarrow x = 40$
Therefore,
Fraction of ${A}^{+2} = \cfrac{\text{atoms of } {A}^{+2}}{\text{Total no. of atoms}}$
$\Rightarrow$ Fraction of ${A}^{+2} = \cfrac{40}{80} = 0.50$

Multiple choice imperfections in solids solid state the solid state chemistry

The non-stoichiometric compound, titanium monoxide has a continuous range of composition from $Ti _{0.75}O$ to $TiO _{0.69}$ Which of the following is/are the correct regarding the possible composition of the compound ? $[Ti=48]$

  1. The maximum percentage by mass of oxygen in the compound is $30.8$
  2. The minimum percentage by mass of titanium in the compound is $69.2$
  3. The minimum percentage by mass of oxygen in the compound is $18.7$
  4. The minimum percentage by mass of titanium in the compound is $82.3$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following defect, if present, lowers the density of the crystal?

  1. Frenkel

  2. Schottky

  3. Metal excess defect due to excess cation

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

Schottky defects involve the removal of ions from the lattice, which decreases the total mass of the crystal for the same volume, thus lowering the density.

Multiple choice imperfections in solids solid state the solid state chemistry

The only incorrect effect on density by the given defect in solids is

  1. Density must decrease by vacancy defect

  2. Density must increase by the interstitial defect

  3. Density must increase by impurity defect

  4. Density does not change by dislocation defect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Vacancy defects decrease density because atoms leave the lattice. Interstitial defects increase density by adding atoms to voids. Impurity defects can either increase or decrease density depending on the size and mass of the impurity, but the statement that it must increase is not a universal rule, making it the most incorrect general claim.

Multiple choice imperfections in solids solid state the solid state chemistry

The intrinsic or thermodynamic defect is

  1. Schottky defect

  2. Metal excess defect due to excess cation

  3. Metal excess defect due to anion vacancy

  4. Metal-deficient defect
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Schottky defects are intrinsic or thermodynamic defects because they arise naturally in ionic crystals due to thermal vibrations, leading to the formation of vacancy pairs to maintain electrical neutrality.