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 chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Which has highest specific charge?

  1. $Na^{+}(mass\ no\ =23)$
  2. $Mg^{2+}(mass\ no\ =24)$
  3. $Al^{+3}(mass\ no\ =27)$
  4. $Si^{+4}(mass\ no\ =28)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Specific charge in the ratio of charge of ion to its mass.

Specific charge $=\dfrac { e }{ M } $
For ${ Na }^{ + }=\dfrac { e }{ 23 } ,\quad $ for ${ Mg }^{ 2+ }=\dfrac { 2\times e }{ 24 } $
For ${ Al }^{ 3+ }=\dfrac { 3\times e }{ 27 } ,\quad $ for ${ Si }^{ 4+ }=\dfrac { 4\times e }{ 28 } $
In is in the following order,
${ Si }^{ 4+ }>{ Al }^{ 3+ }>{ Mg }^{ 2+ }>{ Na }^{ + }$

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

In bisulphate ion, the formal charge on sulphur atom is:

  1. $+1$
  2. $+2$
  3. $+4$
  4. $+6$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the bisulphate ion (HSO4-), the sulphur atom is bonded to four oxygen atoms. One oxygen is bonded to hydrogen, and the others are double-bonded or single-bonded with negative charges to satisfy the octet rule, resulting in a formal charge of +2 on the central sulphur atom.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Formal charge on nitrogen and oxygen in $NO^- _3$ ion are respectively: 

  1. $0, \dfrac{-1}{3}$
  2. $+1, \dfrac{-1}{3}$
  3. $+1, \dfrac{-2}{3}$
  4. $0, \dfrac{-2}{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Formula change is basically a change given to an atom, on assuming that the electrons in a chemical bond are shared equally between the atoms, neglecting theirrelative, $EN.$

$FC=V-N-\cfrac{B}{2}$       $(V=\text{no. of valance electron}\N=\text{No. of non bonding electrons}\B=\text{No. of electrons in covalent bond})$
$FC$ on $N$ in $NO^- _3=0$
$FC$ on $O$ in $NO _3^-=\cfrac{-1}{3}$

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Formal charge on nitrogen in $NO _{3}^{-}$ ion is

  1. $+1$
  2. $+2$
  3. $+5$
  4. $Zero$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the nitrate ion (NO3-), the nitrogen atom is at the center bonded to three oxygen atoms. Using the formal charge formula, nitrogen has 5 valence electrons, 0 lone pair electrons, and 8 bonding electrons (4 bonds), resulting in 5 - 0 - 4 = +1.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

In the cyanide ion the formal negative charge is on:

  1. $C$
  2. $N$
  3. both $C$ and $N$
  4. resonate between $C$ and $N$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the cyanide ion the formal negative charge resonates between $C$ and $N$. Cyanide ion has resonating structure, $-\overset { \ _ }{ C } \equiv N\longleftrightarrow \overset { \ _ }{ N } \underrightarrow { = } C$

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

A molecule with highest bond energy is:

  1. Fluorine

  2. Chlorine

  3. Bromine

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

Bond dissociation energy in $KJ mol^-1$
$F _2-158$
$Cl _2-244$ 
$Br _2-93$ 
$I _2-151$ 
Hence, in order of decreasing bond strength: 
$Cl _2>Br _2>F _2>I _2$
Fluorine is an anomaly. 

Bond strength decreases from chlorine to iodine as down the group, the atomic size becomes larger and thus the valence electron orbitals become more diffused, causing the overlap of orbitals to become less effective. Therefore the halogen-halogen bond becomes weaker from chlorine to iodine.Fluorine is an exception due to its extremely small size. The F-F bond length is so short that the lone pairs of electrons on the fluorine atoms repel each other and weakens the F-F bond. 

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

In which of the following molecules partial charge separation does not take place?

  1. Chlorine

  2. Hydrochloric acid

  3. Water

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

Cl molecules are covalent in nature so it is non polar molecule. Non polar compound consists of molecules linked through chemical bonds arranged in such a way that the distribution of charges are symmetrical. Non polar bonds do not exhibit polarity and do not form ions in their solution. These compounds do not dissolve in water which is a polar molecule.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

The partial charge separation between the bonded atoms gives rise to ___________ in that compound.

  1. covalent character

  2. coordinate character

  3. ionic character

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

Partial charge separation between the bonded atoms gives rise to ionic character in the molecule due to the electronegativity difference, a quite small degree of polarization occurs.

Multiple choice chemistry classification of elements- the periodic table periodic trends in physical properties properties and trend trends in periodic table electronic configuration and valency electron configuration

The ionic radii of ${Rb}^{+}$ and ${I}^{-}$ are $1.46$ and $2.16$ $\mathring { A } $, respectively. The most probable type of structure exhibited by it is

  1. $CsCl$ type
  2. $NaCl$ type
  3. $ZnS$ type
  4. $Ca{F} _{2}$ type
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The radius ratio is calculated as r+/r- = 1.46 / 2.16 = 0.676. A radius ratio between 0.414 and 0.732 indicates an octahedral coordination geometry, which corresponds to the NaCl crystal structure.