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 introduction to organic chemistry bonding in organic molecule tetravalence of carbon: shapes of organic compounds introduction to carbon and its compounds

In $Fe(CO) _5$, the $Fe-C$ bond possesses:

  1. $\pi$ - character only
  2. both $\sigma$ and $\pi$ - characters

  3. ionic character
  4. $\sigma$ - character only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
It's called “synergic bonding”. The ligand (CO) donates it's lone pair of electrons to the vacant orbitals of the iron atom and forms the sigma-bond. Since the iron atom also possesses some electrons in it's d-orbitals, it back donates those electrons to the molecular orbitals of the ligand forming a π-bond. In this way, the metal-carbon bond length is reduced and the complex gets more stability. One important thing to keep in mind is that the metal atom donates it's electron pairs to the antibonding MO of CO, so the C-O bond is weakened by this synergic bonding, leading to a larger C-O bond length in the complex (as opposed to a free CO molecule).
Metal-C bond length reduces, C-O bond length increases, complex gets stability.
Hence, option $B$ is correct.
Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the following is an example of weak electrolyte?

  1. $H _3BO _3$
  2. $H _2SO _4$
  3. $HNO _3$
  4. $HClO _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Boric acid is very weak acid since it dose not give $H^+$ , instead it takes $OH^-$ from $H _2O$ and become $B{ \left( OH \right)  } _{ 4 }^{ - }$ and Proton is lost from $H _2O$ not from boric acid.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Degree of ionisation does not depend on:

  1. nature of the solvent

  2. nature of the electrolyte

  3. dilution

  4. molecular mass of the electrolyte
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Degree of ionization $(\alpha)$ depends on-

1) Concentration of solute
2) Temperature
3) Nature of electrolysis
4) Nature of solvent
5) Dilution
"$\alpha$" does not depend on molecular mass of electrolyte.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Two elements have electronegativity of 1.2 and 3.0. Bond formed between them would be ________________.

  1. predominantely ionic

  2. predominantely covalent

  3. co-ordinate bond

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

Difference of electronegativity between the two atoms is 1.8 so the bond would be predominantly ionic and less covalent. For a bond to be 50% ionic and 50% covalent, the difference between electronegativities should be equal to 1.7.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the following compounds will be dissociated into its constituent ions?

  1. Solid $NaCl$
  2. Molten $NaCl$
  3. Solid $CaCl _2$
  4. Molten $CaCl _2$
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

When electric current is passed through an electrolyte in its molten or aqueous state, the electrolyte is dissociated into its constituent ions.
Molten $NaCl$ breaks down to form $Na^+$ and $Cl^-$ where Sodium transfers its valence electron to Chlorine. So Sodium gets one positive charge and Chlorine gets one negative charge.
Molten $CaCl _2$ breaks down to form $Ca^{2+}$ and two $Cl^-$ ion where Calcium transfers its two valence electron to Chlorine. Hence Calcium gets two positive charges and each Chlorine atom gets one negative charge.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the following compounds will be dissociated into its constituent ions?

  1. Aqueous $KCl$
  2. Solid $KCl$
  3. Aqueous $MgCl _2$
  4. Solid $MgCl _2$
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

When electric current is passed through an electrolyte in its molten or aqueous state, the electrolyte breaks up into its constituent ions.
When aqueous $KCl$ undergoes electrolysis, the ions $K^+$ and $Cl^-$ are formed where potassium transfers its one valence electron to Chlorine. So potassium becomes positively charged and chlorine becomes negatively charged.
When aqueous $MgCl _2$ undergoes electrolysis, the ions $Mg^{2+}$ and two $Cl^-$ ions are formed where magnesium transfers its two valence electron to chlorine. Thus magnesium gets two positive charges and each chlorine gets one negative charge.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

$NaCl \longrightarrow Na^+ +Cl^-$
The above reaction is ionization or dissociation?

  1. Dissociation

  2. Ionization

  3. Both ionization and dissociation

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

Dissociation is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into smaller particles such as atoms, ions or radicals, usually in a reversible manner.

Hence, $ NaCl(aq.)\quad \rightleftarrows \quad { Na }^{ + }(aq.)\quad +\quad { Cl }^{ - }(aq.) $  is a dissociation reaction.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

What is a net ionic equation?

  1. An equation that includes only the substances that are actually participating in the reaction.

  2. An equation that includes all the substances that are in the reaction.

  3. A equation written so that all ions are shown.

  4. An equation written so all charges are balanced on each side.

  5. An equation that includes only ions.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A net ionic equation is an equation that includes only the substances that are actually participating in the reaction.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the followings is/are dissociation and not ionization?

  1. $H _2O \rightarrow H^+ + OH^-$
  2. $HCl \rightarrow H^+ + Cl^-$
  3. $Cl _2 \rightarrow 2Cl^.$
  4. $KCl \rightarrow K^+ + Cl^-$
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

Dissociation is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into smaller particles such as atoms, ions or radicals, usually in a reversible manner.

$ { Cl } _{ 2 }\rightarrow 2{ Cl }^{ \bullet  } $ - Radical formation is there.

$ KCl\rightarrow { K }^{ + }+{ Cl }^{ - } $ - Ion formation is there.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Which of the following is/are ionization and not dissociation?

  1. $HCl \rightarrow H^+ + Cl^-$
  2. $Mg^+ \rightarrow Mg^{2+} + e^- $
  3. $Br _2 \rightarrow 2Br^.$
  4. $HBr \rightarrow H^+ + Br^-$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

In dissociation separation of ions take place which are already present as ions in the solid state. For example in the crystal structure of $NaCl$, $NaCl$ is present as $Na$ and $Cl$.

 In ionization, splitting of a neutral molecule into ions which are charged happen.
$HCl$ and $HBr$ are neutral $\mu $, there is no charge separation. But in solution they get ionised.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Which of the following pairs of ions makes the water hard?

  1. $Na^+$
  2. $Cs^+$
  3. $Rb^+$
  4. $Ba^{+2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ion-exchange resin can soften both temporary and permanent hard water. The ion-exchange resin starts with sodium ions struck to it. As the bond water passes through the column, sodium ions come off the resin and go into the water.

Thus, ${ Na }^{ + }$ ions makes the water hard.

Multiple choice chemistry group 17 group 17 - physical properties physical properties of group 17 elements group 17 elements: the halogen family

The electron affinity values (in kJ $mol^{-1}$) of three halogens X, Y and Z are respectively$ -349, -333 $and $-325$.


 X, Y, and Z respectively are :

  1. $F _2, Cl _2, Br2$
  2. $Cl _2, F _2$ and $Br _2$
  3. $Cl _2, Br _2, F _2$
  4. $Br _2, Cl _2$ and $F _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the values electron affinity the  three halogens X, Y and Z are $Cl _2$,$F _2$ and $Br _2$

Hence option B is correct

Multiple choice chemistry group 17 group 17 - physical properties physical properties of group 17 elements group 17 elements: the halogen family

Which of the following possesses the highest bond energy?

  1. $F _2$
  2. $Cl _2$
  3. $Br _2$
  4. $I _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$F _2$ is a smaller molecule than $Cl _2$. This means that the bonded electrons in $F _2$ are closer to the outer shell unbonded electrons. Due to the electron repulsion theory, the bonded electrons repel the outer shell unbonded electrons far more in $F _2$ than they would in $Cl _2$. 


since  $Cl _2$ has more shells so more shielding of the outer electrons. The fact that the bonded electrons in $F _2$ repel the unbonded electrons so much makes the molecule weak, so it is easier to break. 


Hence option B is correect.