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 p- block elements-ii compounds of phosphorus- pcl5 phosphorus halides compounds of phosphorus compounds of phosphorus - pcl3

The compound molecular in nature in gas phase but ionic in solid state is :

  1. $ PCl _5 $
  2. $ CCl _4 $
  3. $ PCl _3 $
  4. $ POCl _3 $

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

In gaseous and molten state $PCl _5$ is neutral molecule with trigonal bipyramidal symmetry.

In solid state $PCl _5$ is ionic which forms $PCl _4^{+}$, $PCl _6^{-}$. The cation and anion $PCl _4^{+}$, $PCl _6^{-}$ are tetrahedral and octahedral respectively.

Hence option A is correct.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

According to  molecular orbital theory, the paramagnetism of $O _{2}$  molecule is due to presence of 

  1. Unpaired electrons in the bonding $\sigma $ molecular orbital
  2. Unpaired electrons in the anti- bonding $\sigma $ molecular orbital
  3. Unpaired electron in the bonding $\pi $ molecular orbital
  4. Unpaired electrons in the anti - bonding $\pi $ molecular obrital
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

According to molecular orbital theory, the electronic configuration of the oxygen molecule places its last two electrons into degenerate anti-bonding pi star molecular orbitals. Because these two electrons remain unpaired, the O2 molecule exhibits paramagnetism.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

Which of the following is paramagnetic  in nature ? 

  1. $N _{2}$
  2. $C _{2}$
  3. $B _{2}$
  4. $O _{2}^{2+}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Molecular orbital theory shows that B2 has 10 electrons in bonding orbitals and 4 in antibonding, resulting in a bond order of 1 and two unpaired electrons in pi 2p orbitals, making it paramagnetic. O2 2+ has 14 electrons and is diamagnetic, while N2 and C2 are also diamagnetic with all paired electrons.

Multiple choice applications of adsorption adsorption adsorption and colloids surface chemistry chemistry

Lake test of $Al^{3+}$ ion is based on adsorption of blue litmus on solid surface of :

  1. $Al$
  2. $Al(OH) _3$
  3. $Al _2O _3$
  4. $AlCl _3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lake test of $Al^{3+}$ ion is based on adsorption of blue litmus on solid surface of $Al(OH) _3$. The dye aluminon is adsorbed by the gelatinous $Al(OH) _3$ precipitate to form lake coloured solution. This test is used as a confirmatory test for $Al^{3+}$ after precipitation of $Al(OH) _3$ with aqueous ammonia.

Multiple choice chemistry nature of things objects that float or sink substances that sink or float soluble and insoluble substances

In the solvation of $NaCl$ in water, which of the following occur ?

  1. Hydrogen atom interacts with $Cl^-$ atom
  2. Oxygen atom interacts with $Na^+$ atom
  3. Both $A$ and $B$

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

In the water molecule oxygen has higher electronegativity than hydrogen thus has a partial negative charge and hydrogen has a partial positive charge. So during the solvation of NaCl in water, hydrogen atoms interact with chlorine anion and oxygen interact with sodium cation.

Multiple choice

What type of ions do bases release into a solution?

  1. Nitrogen ions

  2. Hydrogen ions

  3. Hydroxide ions

  4. Sodium ions
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the Arrhenius definition, bases are substances that dissociate in aqueous solution to release hydroxide ions (OH-).

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

In the series $Sc(Z=21)$ to $Zn(Z=30)$, the enthalpy of atomisation of which element is least?

  1. Sc

  2. Mn

  3. Cu

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

$Sc\  \& \ Zn$ belongs to the third group of the periodic table. The extent of metallic bonding an element undergoes decides the enthalpy of atomization. The more extensive the metallic bonding of an element, the more will be its enthalpy of atomization. In all transition metals, there are some unpaired electrons that account for their stronger metallic bonding. 

Due to the absence of these unpaired electrons, the inter-atomic electronic bonding is the weakest in $Zn$ and as a result, it has the least enthalpy of atomization.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The Born Haber cycle below represents the energy changes occurring at 298K when KH is formed from its elements
v : ${ \Delta H } _{ atomisation }$ K = 90 kJ/mol
w : ${ \Delta H } _{ ionisation }$ K = 418 kJ/mol
x : ${ \Delta H } _{ dissociation }$ H = 436 kJ/mol
y : ${ \Delta H } _{ electron affinity }$ H = 78 kJ/mol
z : ${ \Delta H } _{ lattice }$ KH = 710 kJ/mol

In terms of the letters v to z the expression for
${ \Delta H } _{ i }$ of K is ${ \Delta H } _{ i }$ = $w/2$.
If true enter 1, else enter 0.

  1. 0

  2. 1

  3. 2

  4. 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In terms of the letters v to z the expression for
${ \Delta H } _{ i }$ of K is ${ \Delta H } _{ i }$ = $w$.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

The Born Haber cycle below represents the energy changes occurring at 298K when KH is formed from its elements
v : ${ \Delta H } { atomisation }$ K = 90 kJ/mol
w : ${ \Delta H } _{ ionisation }$ K = 418 kJ/mol
x : ${ \Delta H } _{ dissociation }$ H = 436 kJ/mol
y : ${ \Delta H } _{ electron affinity }$ H = 78 kJ/mol
z : ${ \Delta H } _{ lattice }$ KH = 710 kJ/mol

In terms of the letters v to z the expression for
${ \Delta H } _{ electron affinity }$ of H is ${ \Delta H } _{ electron affinity }$  is _.
I

  1. $y$
  2. $y/2$
  3. $2y$
  4. $y/3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The electron affinity $\Delta { H } _{ electron\: affinity }$  of an atom or molecule is defined as the amount of energy  released when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion. It is exothermic as heat energy is released from the system.

$\Delta { H } _{ electron\: affinity }$ should be y not y/2.
Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

Select correct statement.

  1. Both lattice energy and hydration energies decrease with ionic size.

  2. Lattice energy can be calculated using Born-Haber cycle.

  3. If the anion is larger compared to the cation, the lattice energy will remain almost constant within a particular group.

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

All the given statements are correct.
(A) Both lattice energy and hydration energies decrease with ionic size With large size, the charge is more dispersed. hence, the extent of hydration is smaller. Also the packing is inefficient.
(B) Lattice energy can be calculated using Born-Haber cycle The BornHaber cycle is an approach to analyze reaction energies. The cycle is concerned with the formation of an ionic compound from the reaction of a metal  (often a Group I or Group II element) with a halogen.
(C) If the anion is larger compared to the cation, the lattice energy will remain almost constant within a particular group

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

Which of the following bonds has the highest bond energy?

  1. Si-Si

  2. Si=Si

  3. Si-O

  4. Si=O
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Bond energy generally increases with bond order. Si=O is a double bond and involves a highly electronegative atom, leading to a very strong bond compared to single bonds or Si-Si bonds.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

Born Haber cycle is used to determine:

  1. electron affinity

  2. lattice energy

  3. crystal energy

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

The Born-Haber cycle is a thermodynamic cycle used to calculate lattice energy by relating it to other measurable quantities like electron affinity, ionization energy, and enthalpy of sublimation.

Multiple choice chemistry lattice energy born-haber cycle born-haber cycles energy cycles

For the maximum ionic character during bond formation ,_________ on cation and a __________ anion are required.

  1. low charge, high charge

  2. low charge, low charge

  3. high charge , no charge

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
For an ionic interaction, both the cation and the anion should possess low charges. If the degree of polarization is quite small, ionic bonds are formed,
Otherwise, with higher degree of polarization, covalent bonds are formed
Ionic bonds result from a redox reaction in which the atoms of an element , which (usually metal) has low ionization energy, give away some of their electrons to achieve a stable electronic configuration
Multiple choice chemistry chemical bond and chemical equation properties of covalent compounds types of bonds and properties covalent bond

Which statement about bonding is not correct?

  1. Carbon can form four single covalent bonds

  2. Chlorine atoms react to gain a noble gas electronic structure

  3. Covalent bonding involves losing and gaining electrons
  4. Hydrogen molecules have the formula $H _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation


Solution:- (C) Covalent bonding involves losing and gaining electrons

Covalent bonding involves sharing of electrons while the losing and gaining of electrons is found in ionic bonding.