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 bond and chemical equation properties of covalent compounds types of bonds and properties covalent bond

$A,\ B,\ C$ are three substances. $A$ does not conduct electricity in the solid, molten state and aqueous solution. $B$ conducts electricity both in the fused and aqueous states, while $C$ conducts electricity only in the aqueous state. In solid state neither $B$ nor $C$ conducts electricity. Which of the following statements is/are true regarding $A,\ B$ and $C $?

  1. $A$ has polar covalent linkage
  2. $A$ has non-polar covalent linkage
  3. $B$ is ionic in nature

  4. Cation has polar covalent bonds
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation
$A$ does not conduct electricity in the solid and molten state suggests that $A$ is not an ionic compound and it can be a covalent compound.
$A$ is not conducting electricity in aqueous solution also, it suggests that all the element in compound $A$ has the same electronegativity.
Hence, $A$ can be non-polar covalent compound that means it has non-polar covalent linkage.
$B$ conducts electricity in a fused state and in aqueous states, This represents that the electronegativity difference in the compound is very high.
Hence, $B$ can be an ionic bond
$C$ conducts electricity in only in the aqueous state. It means that $C$ does not conduct electricity in a molten state that means $C$ is not an ionic compound.
It can be a covalent compound and as it is conducting electricity in the aqueous state, there must be small electronegativity difference.
Hence, $C$ can be a polar covalent compound.
Multiple choice chemistry d- and f-block elements actinoids the actinoids the d-and f-block elements comparison of lanthanoids and actinoids

The bonds generally formin compounds of Actinoids are:

  1. convalent

  2. ionic

  3. coordinate covalent

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

Actinoids are highly electropositive elements, and their compounds are predominantly ionic in nature due to the large size of the ions and the relatively low electronegativity of the metals.

Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Which of these ions are involved in muscle contraction? 

  1. $Ca^{2+}$ and $Mg^{2+}$
  2. $Ca^{2+}$ and $Na^+$
  3. $Na^+$ and $K^+$
  4. $Mg^{2+}$ and $K^+$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Active sites for myosin(Thick filament) are present on actin which are masked by troponin in resting state. when  Ca++ level increases it leads to the binding of calcium with a subunit of troponin on actin(thin) filaments and thereby remove the masking of active sites for myosin.
  • Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge. 
  • This pulls the attached actin filaments towards the centre of ‘A’ band.
  •  The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction.
  • Magnesium also plays a role in regulating muscle contractions. Magnesium acts as a natural calcium blocker to help muscles relax. Hence Ca++ and Mg++ ions are involved in muscle contractions.
  • So, the correct answer is 'Ca$^{2+}$ and Mg$^{2+}$'.
Multiple choice biology locomotion and movement locomotion in animals bones and movements muscle contraction types of muscles muscles

Ion connected with forming cross bridges is

  1. $Na^+$
  2. $Ca^{2+}$
  3. $K^+$

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

Cross bridge cycling forms the basis for movements and force production in the muscle cells. The myosin heads are known as cross bridges because they can bind and move along actin filament. Sarcomere is a stretch of myofibril between two z lines where myosin is in center and actin at periphery, slightly overlapping myosin. Nerve impulse causes release of calcium ions from sarcoplasmic reticulum and binds to troponin which changes configuration of tropomyosin and exposes cross bridge heads on myosin allowing actin myosin binding. This causes contraction of muscle fibre. ATP is required for myosin to dissociate from actin. The calcium ions released from sarcoplasmic reticulum regulate when cross bridging cycle can occur. 

Therefore option B is correct

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

The most resistant organic substance which can withstand environmental extremes and cannot be degraded by any enzyme is 

  1. Lignin

  2. Suberin

  3. Cutin

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

Sporopollenin is found in outer layer or exine of pollen grains. It is extremely resistant and can withstand extremes of temperature presumably as an adaptation to protect the male gametophyte. The exine is weak at few points where sporopollenin is missing. These are germ pores from where pollen germinates that is, pollen tube protrudes out during  germination.

So, the correct answer is 'Sporopollenin'

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The stability of an ionic compound is mostly due to:

  1. ionization energy

  2. electron affinity

  3. lattice energy

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

Lattice energy is a measure of energy released in ionic crystals when the ions are brought together from infinity. It measures the attraction between ions so that they are held in a position. Ionic compound stability is mostly due to lattice energy.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

Lattice energy of ionic compounds depend upon:

  1. packing of ions only

  2. charge and size of ions

  3. charge on ion only

  4. size of ions only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Lattice energy is defined as the heat of formation for ions of opposite charge in the gas phase to combine into an ionic solid. It is directly proportional to the charge on the ions and inversely proportional to the size of the ions. 

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The lattice energy of four ionic compounds $W, X, Y,$ and $Z$ are measured. The energies are found to be $-922\ kJ/mol, -769\ kJ/mol, -718\ kJ/ mol,$ and $-688\ kJ/mol$ respectively.
The four ionic, compounds are $NaCl, NaF, KBr$, and $KCl$.
Which of these ionic compounds could be identified as compound X based on the lattice energy?

  1. $NaCl$
  2. $NaF$
  3. $KBr$
  4. $KCl$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lattice energy magnitude increases with smaller ionic radii and higher charges. Among the compounds, NaF has the smallest ions and highest lattice energy, while KBr has the largest ions and lowest lattice energy. NaCl falls in the middle range.

Multiple choice chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

The correct order of the lattice energies of the following ionic compound is :

  1. $NaCl > MgBr _2 > CaO > Al _2O3$
  2. $NaCl > CaO > MgBr _2 > Al _2O _3
    $
  3. $Al _2O _3 > MgBr _2 > CaO > NaCl$
  4. $Al _2O _3 > CaO > MgBr _2 > NaCl$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Charge matter in lattice energy so here $Al^{+3}, Ca^{+2}, Mg^{+2}, Na^+$ and $O^{-2}$ & $Br^{-1}$
So $cao>MgBr _2 \Rightarrow$ overall order $Al _2O _3>Cao>MgBr _2>NaCl.$

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

If combining atoms of a compound have nearly similar electronegativities the bond between them is_____

  1. electrovalent

  2. covalent

  3. metallic

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

A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.
So, combining atoms of a compound have nearly similar electronegativities the bond between them is covalent.

Multiple choice chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

Which of the following correctly represents symbol for chlorine in Berzelius system?

  1. M

  2. Cl

  3. Mn

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

M correctly represents a symbol for chlorine in Berzelius system. The symbol M was derived from the word Muriatic Radicle which signifies element chlorine. At present, the symbol M is replaced with symbol Cl.