Chemistry

Chemical Bonding and Molecular Structure

1,420 Questions

This section tests your knowledge of chemical bonding, molecular structure, and hybridization. It covers ionic and covalent bonds, octet rule exceptions, and molecular geometry. These chemistry questions are common in various competitive entrance examinations.

Ionic and covalent bondsHybridisation of elementsOctet rule exceptionsMolecular geometryIntermolecular forces

Chemical Bonding and Molecular Structure Questions

Multiple choice imperfections in solids solid state the solid state chemistry

Missing of one cation and one anion from the crystal lattice is called

  1. ionic defect

  2. crystal defect

  3. schottky defect

  4. frenkel defect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Schottky defect arises due to a vacancies at cation sites and equal number of vacancies at anion sites.

Hence, option C is correct.

Multiple choice imperfections in solids solid state the solid state chemistry

Scotty defect is observed in____________.

  1. $NaCl$
  2. $KCl$
  3. $CsCl$
  4. $BaCl _2$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Schottky defect is the defect which is produced when one cation and anion are missing from their respective positions leaving behind a pair of holes. The crystal as a whole remains neutral because the number of missing positive ions (cations) and negative ions (anions) is the same.
For Schottky defect, co-ordination numbers of the ions should be high., Examples of ionic solids showing this defect are NaCl, CsCl, KCI, KBr etc.
Consequences of Schottky defect are as follows:
1. Density of the crystal decreases.
2. The crystal begins to conduct electricity to small extent by ionic mechanism.
3. The presence of too many voids lowers lattice energy or the stability of the crystal.

Multiple choice imperfections in solids solid state the solid state chemistry

Ionic solids with Schottky defects contain in their structure

  1. equal number of cations and anions vacancies

  2. interstitial anions and anion vacancies

  3. cation vacancies only

  4. cation vacancies and interstitial cations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Schottky defect is the defect which is produced when one cation and anion is missing from their respective positions leaving behind a pair of holes. The crystal as a whole remains neutral because the number of missing positive ions (cations) and negative ions (anions) is the same.

Multiple choice imperfections in solids solid state the solid state chemistry

Schottky defect is noticed in:

  1. $NaCl$
  2. $KCl$
  3. $BeCl _2$
  4. both $A$ and $B$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All alkali metal halides show the Schottky defect due to the formation of excess cations.
Thus Schottky defect will be noticed in $NaCl \; & \; KCl$.
Thus, option $(D)$ is right answer.

Multiple choice imperfections in solids solid state the solid state chemistry

Statement 1: KCl is more likely to show schottky defect while Lil is more likely to show Frenkel defect.
Statement 2: Schottky defect is more likely in ionic solids in which cations and anions are of comparable size while Frenkel defect is more likely is which cations and anions have large differences in their ionic sizes.

  1. Statement-1 is true, Statement-2 is true and Statement-2 is correct explanation for Statement-1

  2. Statement-1 is true, Statement-2 is true and Statement-2 is not the correct explanation for Statement-1

  3. Statement-1 is true but Statement-2 is false

  4. Statement-1 is false but Statement-2 is true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In case of KCl, the cation and the anion are of comparable size while in case of LiI, the cation Li+ is very small as compared to the iodide ion, I-. Hence, KCl is more likely to show Schottky defect while LiI tends to show Frenkel defect. Thus, the statements 1 and 2 are true and 2 is correct explanation of 1.

Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following statements are correct?

  1. Dislocation of ion from lattice site to interstitial site is called Frenkel defect.

  2. Missing of +ve and -ve ions from their respective position producing a pair of holes is called Schottky defect.

  3. The presence of ions in the vacant interstital sites along with lattice point is called interstital defect.
  4. Non-stoichiometric $NaCl$ is yellow solid.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

Frenkel defect: This type of defect is created when an ion leaves its appropriate site in the lattice and occupies an interstitial site. A hole or vacancy is thus produced in the lattice.

Schottky defect: This type of defect is produced when one cation and anion are missing from their respective positions leaving behind a pair of holes.

The presence of ions in the vacant interstital sites along with lattice point is called interstital defect.

 When alkali metal halides are heated in an atmosphere of vapours of the alkali metal, anion vacancies are created. 


The anions (halide ions) diffuse to the surface of the crystal from their appropriate lattice sites to combine with the newly generated metal cations. The electron lost by the metal atom diffuse through the crystal is known as F-centres. 


The main consequence of metal excess defect in the development of colour in the crystal. For example, when $NaCl$ crystal is heated in an atmosphere of $Na$ vapours, it becomes yellow.


Therefore, all statements are correct.

Multiple choice imperfections in solids solid state the solid state chemistry

Which of the following statements is/are correct ?

  1. If three $Fe^{2+ }$ ions are missing from their lattice in FeO, there must be two $Fe^{3+ }$ ions somewhere in the lattice.

  2. Crystals with metal deficiency defects are called super conductors.

  3. Crystals with metal deficiency are called semiconductors.
  4. Bohr Magneton = $9.27 \times 10^{-24} A \:m^2$.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

The statements A, C and D are correct.
(A) If three $Fe^{2+}$ ions are missing from their lattice in FeO,  there must be two $Fe^{3+}$ ions somewhere in the lattice.
The charge on three $Fe^{2+}$ ions is $3 \times (+2) = +6$
The charge on two $Fe^{3+}$ ions is $2 \times{3+} = +6$
Thus, the electrical neutrality is maintained.

Two type of vacancies of iron are present here. This is called crystal with metal deficiency defect.

(B) Crystals with metal deficiency defects are not called super conductors. The idea of Superconductors is that it possesses zero resistance at a certain temperature. 

(C) Crystals with metal deficiency are called semiconductors.

(D) Bohr Magneton = $9.27 \times 10^{-24} A :m^2$.
The orbital or spin magnetic momentum of an electron is expressed in terms of Bohr magneton. Its symbol is $\mu _B$.

Except option B all are correct.

Multiple choice zoology soil pollution industrial chemicals and their harmful effects toxic wastes and their effects soil pollution-causes

When EDTA solution added to ${ Mg }^{ 2+ }$ ion solution, then which of the following statement is not true?

  1. Four coordinates sites of ${ Mg }^{ 2+ }$ are occupied by EDTA and remaining two sites are occupied by water molecules.
  2. All six coordinate sites of ${ Mg }^{ 2+ }$ are occupied

  3. pH of the solution is decreased
  4. Colorless $[{ Mg-EDTA }]^{ 2- }$ chelate is formed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
When EDTA solution added to the Mg2+ion solution, all six coordinate sites of Mg2+ are occupied, and a colourless [Mg−EDTA]2− chelate is formed. This reaction also results in the lowering of the pH of the solution.
So, the correct answer is 'Four coordinates sites of Mg2+ are occupied by EDTA and remaining two sites are occupied by water molecules.'
Multiple choice chemistry chemistry in daily life antimicrobials and antifertility drugs therapeutic action of different classes of drugs drugs and their classification

Compound with antiseptic properties are:

  1. $CHCl _3$
  2. $CHI _3$
  3. $ Boric$ $acid $
  4. $0.3$ $ppm $ $Cl _2$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation
Antiseptics are anti microbial substances that are applied to living tissue or skin to reduce the possibility of infection.
$CHI _3$ and Boric acid $($chemically known as orthoboric acid $(H _3BO _3))$ are used as antiseptics.
Multiple choice chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

The number of simple covalent bonds (B-H) present in diborane:

  1. 2

  2. 4

  3. 6

  4. 8
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The molecular formula of diborane is $B _{2}H _{6}$
Diborane consists 2 3center-2electrons bonds and 4 2center-2electrons bonds.
In diborane, the two boron groups are bonded to each other by a bridge-like structure. Thus, it contains 4 covalent bonds.
Multiple choice chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

Diborane is:

  1. electron-sufficient

  2. electron-deficient

  3. electron-donor

  4. none
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Diborane is electron-deficient i.e, there are not enough valence electrons to form the expected number of covalent bonds. For example, in diborane, there are only 12 electrons, three from each boron atoms and six from hydrogen, while ethane possesses 14 such electrons.

Multiple choice chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

Identify the statement that is not correct as far as structure of diborane is concerned.

  1. There are two bridging hydrogen atoms in diborane

  2. Each boron atom forms four bonds in diborane

  3. All B - H bonds in diborane are similar
  4. Diborane contains 3c-2$e^{-}$ bonds
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In diborane, there are two types of B-H bonds: terminal and bridging. The terminal bonds are standard 2c-2e bonds, while the bridging bonds are 3c-2e bonds. Therefore, they are not all similar.

Multiple choice chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

Which is/are correct for $B _2H _6$ structure ?

  1. It has $1\:B-H$ terminal bonds and two 3C-2e bonds
  2. It has $5\:B-H$ terminal bonds and two 3C-2e bonds
  3. It has $4\:B-H$ terminal bonds and two 3C-2e bonds and one $B-B$ bond
  4. It has ionic interaction between $[BH _2]^+$ and $[BH _4]^-$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the structure of diborane, $4$ terminal $B-H$ bonds are present. These are regular 2C-2e bonds.
In addition, two $B-H-B$ bridges are present. These are 3C-2e bonds.

Multiple choice chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

Find the incorrect match.

  1. $Al _2Cl _6$ : $3C - 4e$ bond is present
  2. $Al _2(CH _3) _6$ : All carbon atoms are $sp^{3}$ - hybridized
  3. $I _2Cl _6$ : Nonplanar
  4. $Al _2Br _6$ : Nonpolar
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A) $Al _2Cl _6$ contains, $3C-4e$ bonds. In each such bond, two $Al$ atoms and one $Cl$ atom participate. Each $Al$ atom contributes $1$ electron and $Cl$ atom contributes $2$ electrons. Thus, the option A is correct.
B) In $Al _2(CH _3) _6$, all $C$ atoms are $sp^3$ hybridized and result in tetrahedral geometry. Thus, the option B is correct.
C) In $I _2Cl _6$, each iodine atom is $sp^3d^2$ hybridized with $4$ bond pairs and two lone pairs. Each iodine atom has square planar geometry. The repulsion between the lone pair of electrons on two iodine atoms will be minimized when the molecule is planar. Thus, the option C is incorrect.
D) $Al _2Br _6$ molecule is non planar as each $Al$ atom is $sp^3$ hybridized. Thus, the option D is correct.