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 nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Which one does not liberate NH3 when undergoes hydrolysis?

  1. Acetaniide

  2. Acetonitrile

  3. Acetamide

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

Acetamide, acetanilide, and acetonitrile all contain nitrogen in forms that can be hydrolyzed to release ammonia or ammonium ions. Phenyl isocyanide (phenyl carbylamine) does not undergo hydrolysis to liberate ammonia.

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Which of the following can be classified as a molecular hydride ?

  1. $LiH$
  2. $\mathrm { NH } _ { 3 }$
  3. $\mathrm { NiHO } _ { 6 }$
  4. $\mathrm { MgH } _ { 2 }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Hydride is the product when hydrogen reacts with any other elements, except the noble gases. So hydrides are compounds where one atom is hydrogen to another more electropositive element. A hydride is an anion of hydrogen $(H^-)$.
Bonding between hydrogen & other elements is always covalent. General chemical formula of a hydride is $MH _{x}$ where   $M=$ other element with hydrogen makes a binary compound. $x=$ no. of hydrogen atoms.
Covalent or Molecular hydrides
Hydrogen atoms from a covalent bond with $p-$block atoms. General chemical formula$-XH _{(8-n)}$ where $n=$no. of electrons the element has in its atomic shell.
$NH _{3}$ is $c$ molecular hydride
$3H _{2(g)}+N _{2(g)}\rightarrow 2NH _{3(g)}$
Answer is $B)\ NH _{3}$

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Which of the following has highest proton affinity:

  1. Stilbine

  2. Arsine

  3. Phosphine

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

As the size of the nitrogen in ammonia is less than the other elements in the hydrides of that group ammonia has the more affinity towards the proton than the any other hydride of that group like phosphine, stobine and arsine.
Hence option D is correct.

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Geometry of ammonia molecule and the hybridisation of nitrogen involved in it are: 

  1. $sp^3$- hybridisation and tetrahedral geometry
  2. $sp^3$- hybridisation and distorted tetrahedral geometry
  3. $sp^2$- hybridisation and trianguklar geometry

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

(i) Hybridisation $= \frac{1}{2}$ [no.of $e^-$ in valence shell of central atom + no. of monovalent atoms + charge on anion - charge on cation]
(ii) Shape or geometry of molecule depends on lone pair and bond pair of electrons present in it.
Hybridisation  of N in $NH _3$
$=\frac{1}{2}(5+3+0)$
$=4$
$\therefore sp^3$ hybridisation.
$\because$, its has 3 bond pair and 1 lone pair of electrons, so it has distorted tetrahedron shape. 

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

The two ions which are formed when ammonia dissolves in water are ammonium ion and ___________ .

  1. ${ OH }^{ - }$
  2. ${ H _3O }^{ + }$
  3. ${ H }^{ +}$
  4. ${ O }^{ -2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ammonia readily dissolves in water with the liberation of heat. The ions which are formed are ammonium ion and hydroxyl ion. The aqueous solution of ammonia is ammonium hydroxide.
$ { NH } _{ 3 }+{ H } _{ 2 }O\rightleftharpoons { NH } _{ 4 }^{ + }+{ OH }^{ - }$

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Which has the highest $pK _b$ value ?

  1. $R _3N$
  2. $R _2NH$
  3. $RNH _2$
  4. $NH _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ammonia is a weak base so it has pK value of 4. So the order of basicity is ammonia<primary<tertiary amines <secondary amines. This order depends on steric hindrance. The size of alkyl group is more than that of hydrogen atom. So alkyl group hinders the attack of hydrogen atom and decreases the basicity of molecule. So more the number of alkyl groups lesser will be its basicity.

Multiple choice chemistry nitrogen and sulfur ammonia-properties and uses ammonia compounds of nitrogen - ammonia

Which of the following forms hydrogen bond?

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

Hydrogen bonding occurs when hydrogen is covalently bonded to a highly electronegative atom like nitrogen, oxygen, or fluorine. Ammonia (NH3) satisfies this condition.