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 further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

The common ion effects is shown by which of the following sets of solutions:-

  1. $BaCl _{2}+Ba(NO _{3}) _{2}$
  2. $NaCl+HCl$
  3. $NH _{4}OH+NH _{4}Cl$
  4. $None$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Common ion effect is normally applied in selective precipitation of ions which involves a technique of separating ions in an aqueous solution by using a reagent that precipitates one or more of the ions. addition of common ions in a solution that is already having that given ion normally leads to a formation of a precipitate. The common ion normally decreases the solubility of a slightly insoluble salt.

Its not (1) because they are both solids.

The remaining are solute solvent pairs. So all the other pairs will show common ion effect if the solute is soluble to some extent and exists in an equilibrium with the solvent. The answer given is (3).

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

In the presence of a common ion (incapable of forming complex ion), the solubility of salt _______  in solution.

  1. increases

  2. decreases

  3. remains the same

  4. cannot predict
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$AB \rightarrow A^+ + B^-$
$BC \rightarrow B^+ + C^-$
Since $B^+$ is incapable of forming a complex salt it tends to decrease the solubility by Le-Chatelier's principle.

Multiple choice chemistry chemical equilibrium and acids-bases dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

In a $0.1\ M$ solution of $H _{3}PO _{4}$ the ionic species present are (besides $H _{3}O^+$ and $OH^{-}$):

  1. ${H _{2}PO _{4}}^{-}, {HPO _{4}}^{2-}, {PO _{3}}^{3-}$
  2. ${H _{2}PO _{2}}^{3-}, {H _{2}PO _{4}}^{-}, {PO _{4}}^{3-}$
  3. ${H _{2}PO _{4}}^{-}, {HPO _{3}}^{2-}, {PO _{2}}^{3-}$
  4. ${PO _{3}}^{4-}, {PO _{4}}^{3-}, {HPO _{4}}^{2-}, {H _{2}PO _{4}}^{-}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$H _3PO _4$$=$$H^+$$+$$H _2PO _4^-$

$H _2PO _4^-$$=$$H^+$$+$$HPO _4^{-2}$
$HPO _4^{-2}$$=$$H^+$$+$$PO _4^{-3}$
Thus $H _3PO _4$ will dissociate into the ions $H _2PO _4^-$, $HPO _4^{-2}$, $PO _4^{-3}$.
Option A is the correct answer.

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

What is the net effect of the common ion?

  1. It reduces the solubility of the solute in the solution.

  2. It reduces the increases of the solute in the solution.

  3. It causes more product to be made.

  4. It causes more ions to form.

  5. There is no net effect overall.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The net effect of the common ion is that it reduces the solubility of the solute in the solution.
The common ion effect is observed when the addition of an ion common to two solutes causes precipitation or reduces ionization.
Thus, if to a solution of weak electrolyte, a solution of strong electrolyte is added which furnishes an ion common to that furnished by the weak electrolyte, the ionization of the weak electrolyte is suppressed.
For example, ammonium hydroxide is a weak electrolyte and ionizes to a small extent to give ammonium ions and hydroxide ions.
$\displaystyle  NH _4OH \rightleftharpoons NH _4^+  +  OH^-$
A strong electrolyte NaOH is added which furnishes hydroxide ions that are common ions. This suppresses the equilibrium for the dissociation of ammonium hydroxide.
$\displaystyle  NaOH \rightarrow Na^+  + OH^-$

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

What is the common ion effect?

  1. When the addition of an ion common to two solutes causes precipitation or reduces ionization.

  2. When a molecule is added to a solution and causes precipitation or reduces ionization

  3. When the subtraction of an ion common to two solutes causes precipitation or reduces ionization.

  4. The effect of adding ions to a solution.

  5. When any ion is added to a solution and causes precipitation or reduces ionization.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The common ion effect is observed when the addition of an ion common to two solutes causes precipitation or reduces ionization.
Thus, if to a solution of a weak electrolyte, a solution of strong electrolyte is added which furnishes an ion common to that furnished by the weak electrolyte, the ionization of the weak electrolyte is suppressed.

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

Which pair will show common ion effect?

  1. $Ba{ Cl } _{ 2 }+Ba{ \left( { NO } _{ 3 } \right) } _{ 2 }$
  2. $NaCl+HCl$
  3. ${ NH } _{ 4 }OH+{ NH } _{ 4 }Cl$
  4. $AgCN+KCN$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Those ions will show common ion effect in which one or both them does not dissociate completely.


$NaCl$ and $HCl$ dissociate completely as one of them is acid and other is salt of strong acid and strong base.


$AgCN$ and $KCN$ dissociate completely as one of them is acid and other is salt of strong acid and strong base.

NH4OH is weak base to which NH4Cl is added which provides common $NH _4^{+}$ion dissociation of NH4OH is suppressed.

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

Which of the following pairs will show common ion effect?

  1. Barium chloride + barium sulphate

  2. Silver cyanide + potassium nitrite

  3. Ammonium hydroxide + ammonium chloride

  4. Sodium chloride + hydrogen chloride
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The common ion effect occurs when a strong electrolyte and a weak electrolyte share a common ion. Ammonium hydroxide (weak base) and ammonium chloride (strong salt) share the NH4+ ion.

Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

Which of the following has maximum $pK _a$ :-

  1. $CH _2FCOOH$
  2. $CH _3ClCOOH$
  3. $CH _3COOH$
  4. $HCOOH$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct answer is $(A)$.

Because,
$C{H _2}FCOOH$ is the strongest acid in the following:
Hence,
Fluorine is an electron withdrawing group the acidic strength increases.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Which of the following is least stable?

  1. $Tl{I} _{3}$
  2. $Tl{F} _{3}$
  3. $Pb{F} _{4}$
  4. $Pb{I} _{4}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

PbI4 is the least stable because Pb(IV) is a strong oxidizing agent and I- is a strong reducing agent, leading to spontaneous reduction to Pb(II) and I2. In contrast, fluorides are more stable because fluorine is a poor reducing agent.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

_______ is the only member of the halogen family that has no stable isotopes.

  1. $\displaystyle F$
  2. $\displaystyle Cl$
  3. $\displaystyle Br$
  4. $\displaystyle I$
  5. $\displaystyle At$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Astatine has many isotopes, all of which are radioactive in nature. Their half-lives are also very small. Hence, astatine has no stable isotopes.

Option $E$ is the correct answer.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Which of the following non-metals sublimes on heating?

  1. Fluorine

  2. Chlorine

  3. Bromine

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

Iodine crystals sublime because though there are covalently bonded within the molecule holding two iodine atoms together, only Van der Waals' forces exist between the iodine molecules. Van der Waal's forces are very weak interactions between molecules of a substance hence the Iodine molecules can escape from the solid structure easily.

Multiple choice group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

Which of the following halides is inert towards hydrolysis at room temperature? 

  1. ${ SiCl } _{ 4 }$
  2. ${ PCl } _{ 3 }$
  3. ${ NCl } _{ 3 }$
  4. ${ NF } _{ 3 }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Hydrolysis takes place through the coordination with lone pair of electron of water molecule. But neither nitrogen, nor fluorine have vacant d-orbital for coordination. Hence $N{F} _{3}$ behaves as inert towards hydrolysis.