Chemistry

Chemical Bonding and Molecular Structure

1,277 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 coordinate bond types of bonds and properties chemical bond and chemical equation

Which one of the following contains just one sigma bond?

  1. $\displaystyle { H } _{ 2 }$
  2. $\displaystyle { CO } _{ 2 }$
  3. $\displaystyle { H } _{ 2 }O$
  4. $\displaystyle NaCl$
  5. $\displaystyle { CH } _{ 2 }{ CH } _{ 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation


As the valence shell of $H$ atom has single electron and it forms single sigma bond with itself.


Hence the correct option is A.

Multiple choice chemistry chemical bonding and structure coordinate bond types of bonds and properties chemical bond and chemical equation

Which of the following contains a coordinate covalent bond ?

  1. $N _2H^{+} _{5}$
  2. $BaCl _2$
  3. $HCl$
  4. $H _2O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

${ N } _{ 2 }{ H } _{ 5 }^{ + }$ is formed from ${ N } _{ 2 }{ H } _{ 4 }$ which has a lone pair of electrons on $'N'$ and positive charge on $'H'$ takes away its electron and to complete duplet, a co-ordinate bond is present from $N$ to $H$.

$H _4N _2 + H^+ \rightarrow[H _4N _2\to H]^+$

Multiple choice chemistry chemical bonding and structure coordinate bond types of bonds and properties chemical bond and chemical equation

Which of the following molecule has dative bond?

  1. CO
  2. $CO _3^{2-}$
  3. $SO _4^{-2}$

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

Carbon monoxide (CO) contains a dative (coordinate) bond where oxygen donates a lone pair to carbon to complete its octet. While other options also involve coordinate bonding in their Lewis structures, CO is the most classic example of a simple molecule defined by this feature.

Multiple choice chemistry basic concepts of chemistry law of multiple proportion law of multiple proportions laws of chemical combination

Which of the following sets of compounds follow law of multiple proportions?

  1. $NO,\ { NO } _{ 2 }$ and ${ N } _{ 2 }{ O } _{ 5 }$
  2. $CO,\ { CO } _{ 2 }$ and ${ CH } _{ 4 }$
  3. ${ NH } _{ 3 },\ { H } _{ 2 }O$ and ${ NO } _{ 2 }$
  4. ${ H } _{ 2 }O,\ { CO } _{ 2 }$ and ${ CH } _{ 4 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The law of multiple proportions states that when two elements can combine in different ratios to form different compounds, the masses of the element combining with the fixed mass of another element result in the whole-number ratio. 


Hence, for a set of compounds to follow law of multiple proportions, the combining elements must be the same. 

Since the combining element in $NO, NO _2,\ and\ N _2O _5$ are the same, that is Nitrogen and Oxygen. 

Therefore, the correct answer is $A$

Multiple choice chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

Bond energies can be obtained by using the following relation:


$\Delta H(reaction) =\sum$ Bond energy of bonds, broken in the reactants $- \sum$ Bond energy of bonds, formed in the products.

Bond energy depends on three factors:
a. greater is the bond length, lesser is the bond energy
b. bond energy increases with the bond multiplicity
c. bond energy increases with the electronegativity difference between the bonding atoms. Which among the following sequences is correct about the bond energy of $C-C$, $C=C$, and $C\equiv C$ bonds?

  1. $C=C > C \equiv C > C-C$
  2. $C\equiv C < C=C < C-C$
  3. $C\equiv C > C=C > C-C$
  4. $C\equiv C > C-C > C=C$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

bond energy of $C-C  = 347 KJ/mole$
$C=C = 620 KJ/mole$
$C\equiv C =812 KJ/mole$
so order is: 
$C\equiv C > C=C > C-C$

Multiple choice chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

Bond energies can be obtained by using the following relation:
$\Delta H(reaction) =\sum$ Bond energy of bonds, broken in the reactants $- \sum$ Bond energy of bonds, formed in the products
Bond energy depends on three factors:
a. greater is the bond length, lesser is the bond energy
b. bond energy increases with the bond multiplicity
c. bond energy increases with the electronegativity difference between the bonding atoms.Bond energy of different halogen molecules will lie in the sequences of:

  1. $F _2 > Cl _2 > Br _2 > I _2$
  2. $Cl _2 > Br _2 > F _2 > I _2$
  3. $I _2 > Cl _2 > Br _2 > I _2$
  4. $Br _2 > F _2 > I _2 > Cl _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Bond energy of $F _2$ is low due to lower size of F atoms and strong repulsion between the lone pairs of two fluorine atoms.
Among other halides as size increases bond energy decreases so order is
$Cl _2 > Br _2 > F _2 > I _2$
Multiple choice chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

The bond dissociation energies for single covalent bonds formed between carbon and $A,B,C,D$ and $E$ atoms are:

Bond  Bond energy $kcal{ mol }^{ -1 }$
(i) $C-A$ $240$
(ii) $C-B$ $382$
(iii) $C-D$ $276$
(iv) $C-E$ $486$

This indicates that the smallest atom is:

  1. $A$
  2. $B$
  3. $C$
  4. $E$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$C-E$ bond has highest bond energy; it means that the covalent bond $C-E$ will be strongest. Smaller is the size of atom, stronger is the covalent bond.

Multiple choice chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

Which is the correct order of bond energy of single, double and triple bonds between carbon atoms?

  1. $C-C > C= C > C \equiv C$
  2. $C= C > C \equiv C > C-C$
  3. $C \equiv C > C-C > C =C$
  4. $C \equiv C > C = C > C-C$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Carbon has all 4 valence electrons. So it easily bonds with other carbon atoms to form long chains Carbon atoms. Apart from single bond carbon also forms double bonds in compounds like alkenes or triple bonds in compounds like alkynes.

A carbon-carbon bond is very strong. The carbon to carbon triple bond has dissociation energy of $348 \frac{kJ}{mol}$, followed by a double bond with $614 \frac{kJ}{mol}$ and single bond having $839 \frac{kJ}{mol}$.

 The correct order of bond energy strength is option D.

Multiple choice chemistry energetics and thermochemistry bond energies and enthalpy changes bond enthalpies enthalpies for different types of reactions

Amount of energy required to break a specific covalent bond is called:

  1. Bond dissociation energy

  2. Bond energy

  3. Bond enthalpy

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The energy required to break a specific covalent bond in one mole of gaseous molecules is called the bond energy or the bond dissociation energy or bond enthalpy.


Hence, the correct option is $D$ 

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Compare the bond energy (B.E) of $O-H$ in water and $O-D$ in heavy water:

  1. B.E of $O-H >$ B.E of $O-D$
  2. B.E of $O-H <$ B.E of $O-D$
  3. B.E of $O-H =$ B.E of $O-D$
  4. B.E of $O-H =$ 2 times B.E of $O-D$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Boiling point of heavy water is more than normal water and therefore, bond energy of $O-H$ bond in water is lesser than bond energy of $O-D$ bond in heavy water. 


Also, bond length of $O-H$ is greater than $O-D$ and bond energy is inversely proportional to bond energy.

Multiple choice chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

The most active halogen is:

  1. fluorine

  2. chlorine

  3. bromine

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

The most active halogen is fluorine. This is due to the small size and high electronegativity of Fluorine.

Fluorine, a pale yellow gas, is the least dense and chemically the most active, displacing the other halogens from their compounds and even displacing oxygen from water. Chlorine, a yellow-green gas, is denser and less reactive than fluorine.

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Which of the following is deliquescent?

  1. $ZnCl _2$
  2. $Hg _2Cl _2$
  3. $HgCl _2$
  4. $CdCl _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$(A)$  $ZnCl _{2}$


$Reason$ : Zinc chloride is a chemical compound with the formula $ZnCl _{2}$ and its hydrates.All zinc chlorides are colourless or white and highly soluble in water.Zinc chloride or $ZnCl _{2}$ is a $deliquescent$ salt  and forms acidic solutions in polar organic solvents,such as water, ether and acetone etc.
As we know, $deliquescent$ substances are the water soluble substances which absorbs moisture from the air and then dissolve in the absorbed moisture to change into liquid state and this phenomenon is called $deliquescence$.$ZnCl _{2}$ is one of the example of $deliquescent$ substance.

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Which of the following salts can produce only two types of radicals?

  1. $NaKCO _3$
  2. $CaOCl _2$
  3. $NH _4HSO _4$
  4. $Na(NH _4)HPO _4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$NaKCO _3\rightarrow Na^++K^++CO _{3}^{-2}$
$CaOCl _2\rightarrow Ca^{+2}+OCl^-+Cl^-$
$NH _4HSO _4\rightarrow NH _{4}^{+}+HSO _{4}^{-}$
(2 types of radicals)
$Na(NH _4)HPO _4\rightarrow Na^++NH _{4}^{+}+HPO _{4}^{-}$