Hydrogen Bonding MCQ Quiz - Objective Question with Answer for Hydrogen Bonding - Download Free PDF

Option 3 is correct, i.e. When a hydrogen atom is in between the two highly electronegative atoms.

• There are two types of H bond and they are as follows:
  • Intramolecular hydrogen bond.
  • Intermolecular hydrogen bond.

• Intramolecular hydrogen bond:
  • It is formed when a hydrogen atom is in between the two highly electronegative (F, O, N) atoms present within the same molecule. For example, in o-nitrophenol, the hydrogen is in between the two oxygen atoms.
• Intermolecular hydrogen bond:
  • It is formed between two different molecules of the same or different compounds. For example, H-bond in case of HF molecule, alcohol or water molecules, etc.

CONCEPT:

5. Electronegativity:

• The electronegativity of an atom is defined as the tendency of an atom to attract pair of electrons toward it when combined in a compound.
• In the periodic table, elements on the extreme right part are highly electronegative. For example, fluorine, oxygen, nitrogen, etc.
• Fluorine has the highest electronegativity in the periodic table.

5. Hydrogen bond:

• An electronegative atom has at least one lone pair in order to form a hydrogen bond. For example, oxygen is electronegative and has two lone pairs on it.

• When hydrogen is attached covalently to a highly electronegative atom, the bonding electrons are attracted toward the electronegative atom, resulting in the generation of a partial positive charge on hydrogen and a partial negative charge on the electronegative atom.
• The bond becomes polar due to differences in electronegativity values.

                         H^δ+-------------------X^δ-

            Where, X is an electronegative atom, F, O, N, etc.

• Now, this partially positive hydrogen atom attracts toward the electronegative atom on another molecule.
• This weak electrostatic force of attraction between a covalently bonded hydrogen atom and an electronegative atom of another molecule is called a hydrogen bond.
• Higher the electronegative difference between hydrogen and an electronegative atom, the more polar and the stronger the bond. High energy (heat) requires to break such bonds, which indicates higher boiling points in such compounds.
• Electronegativity values of hydrogen, oxygen, fluorine, and nitrogen are given in the below table

• Hydrogen bonds are weak and may have energy from 4 to 45 kJ mol^-1.

EXPLANATION:

• Here, three molecules, HF, H₂O, and NH₃ are given. All these three contain electronegative atoms F, O, and N respectively.
• HF:
  • Fluorine has one lone pair in the second energy level (K-shell). HF is a linear molecule and has a tendency to form two hydrogen bonds per molecule, one with hydrogen and one with fluorine.

• Fluorine is the most electronegative atom in the periodic table.  Hydrogen bond strength is 29.5 kJ mol^-1. Therefore, for two bonds, it is 60 kJ mol^-1. 
• H₂O:
• Oxygen has two lone pairs in the second energy level (K-shell). H₂O is a v-shaped molecule and has a tendency to form four hydrogen bonds per molecule, two with hydrogen and two with oxygen.
• The geometry of the water molecule allowed the formation of four hydrogen bonds.
  • Hydrogen bond strength is 25 kJ mol^-1. Therefore, for two bonds, it is 100 kJ mol^-1.
  • 
• NH₃:
• Nitrogen has one lone pair in the second energy level (K-shell). NH₃ has pyramidal geometry and has a tendency to form only two hydrogen bonds per molecule, one with hydrogen and one with nitrogen.
• Geometry (spatial arrangement if atoms) of ammonia molecule restricts the formation of hydrogen bonds around whole molecule like a water molecule.
  • Hydrogen bond strength is 15 kJ mol^-1. Therefore, for two bonds, it is 30 kJ mol^-1.
  • 
• Despite of highest electronegativity and hydrogen bond strength, the HF molecule has a lower boiling point than water because, the number of hydrogen bond per molecule for water is four, which increase the overall heat required to break the bonds.
• While ammonia has the lowest boiling point among the given three compounds as hydrogen bond strength is low and geometry restriction for the formation of a greater number of hydrogen bonds around the whole molecule.

Thus, correct option is (2) H₂O > HF >  NH₃ 

Concept:

Intermolecular hydrogen bonding: 

• This type of bonding mainly occurs between two or more same or different molecules when they combine to form a dimer or polymer respectively and leads to a phenomenon known as an association.
• Such a type of hydrogen bonding increases the boiling point of the compound and also its solubility in water. 

Intramolecular hydrogen bonding: 

• This type of bonding occurs within two atoms of the same molecule and leads to a phenomenon known as chelation.
• This type of hydrogen bonding frequently occurs in organic compounds and results in the cyclization (six or five-membered ring) of the molecule. 

Explanation:

• o-nitrophenol has intramolecular hydrogen bonding so it is more volatile.
• So, the statement I is true.
• The lowest melting point of o-isomer is due to intramolecular hydrogen bonding whereas meta and para isomers possess intermolecular hydrogen bonding and thus, they have higher melting points. 
• Thus statement II is false.​

Correct Answer: (3)

Concept:

• Boiling Point:
  • Boiling point is the temperature at which a substance transitions from the liquid phase to the gas phase.
  • The boiling point is influenced by the strength of intermolecular forces present in the substance.
• Intermolecular Forces and Hydrogen Bonding​
  • Different types of intermolecular forces include Van der Waals forces, dipole-dipole interactions, and hydrogen bonding.
  • Stronger intermolecular forces lead to higher boiling points.
  • Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when a hydrogen atom is directly bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine. This results in stronger intermolecular forces and higher boiling points.

Explanation:

1. Dimethyl Ether (\(\text{CH}_3\text{OCH}_3\))
   • Intermolecular Forces: Dimethyl ether primarily exhibits Van der Waals forces and dipole-dipole interactions.
   • Dimethyl ether does not have hydrogen bonding because there is no hydrogen atom directly bonded to an oxygen atom.
2. Ethanol: (\(\text{CH}_3\text{CH}_2\text{OH}\))
   • Intermolecular Forces: Ethanol exhibits Van der Waals forces, dipole-dipole interactions, and strong hydrogen bonding.
   • Hydrogen bonding occurs in ethanol due to the presence of the hydroxyl -OH group, where a hydrogen atom is directly bonded to an oxygen atom.

Conclusion:

Therefore, dimethyl ether has a lower boiling point than ethanol because it lacks hydrogen bonding, which is present in ethanol and significantly increases the boiling point due to the stronger intermolecular forces.

Option 3 is correct, i.e. When a hydrogen atom is in between the two highly electronegative atoms.

• There are two types of H bond and they are as follows:
  • Intramolecular hydrogen bond.
  • Intermolecular hydrogen bond.

• Intramolecular hydrogen bond:
  • It is formed when a hydrogen atom is in between the two highly electronegative (F, O, N) atoms present within the same molecule. For example, in o-nitrophenol, the hydrogen is in between the two oxygen atoms.
• Intermolecular hydrogen bond:
  • It is formed between two different molecules of the same or different compounds. For example, H-bond in case of HF molecule, alcohol or water molecules, etc.

Option 3 is correct, i.e. When a hydrogen atom is in between the two highly electronegative atoms.

• There are two types of H bond and they are as follows:
  • Intramolecular hydrogen bond.
  • Intermolecular hydrogen bond.

• Intramolecular hydrogen bond:
  • It is formed when a hydrogen atom is in between the two highly electronegative (F, O, N) atoms present within the same molecule. For example, in o-nitrophenol, the hydrogen is in between the two oxygen atoms.
• Intermolecular hydrogen bond:
  • It is formed between two different molecules of the same or different compounds. For example, H-bond in case of HF molecule, alcohol or water molecules, etc.

Concept:

Hydrogen bonding:

• Hydrogen bonding is a special type of interaction that occurs between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.
• It is a special type of dipole-dipole interaction.
• Although H-bond is very weak but compounds having H-bond have high melting and boiling point.

There are two types of H-bonding -

1. Intermolecular H-bonding
2. Intramolecular H-bonding

→ Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen. 

Explanation:

The hydrogen bond is a special type of bond between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.

→ Condition for H-Bonding :

Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen.

∴ only F, O, and N are such atoms that can make an H-bond with the hydrogen of other molecules.

In the given compounds HCl, H2O, HI, and H2S only H2O can form H-bond because Cl, S, and I are large size atoms and cannot form H-bond.

∴ Only H₂O will form H-bond 

• Intermolecular H-bonding is there in the water.
• Each H₂O can make four H-bonds. Two with O-atom and two with H-atom.
• Each H₂O molecule is tetrahedrally linked to the four other H₂O molecules.

Conclusion:

Therefore, H-bonding will be strongest in H₂O.

Hence, the correct answer is option 2.

Concept:

Hydrogen bonding:

• It is the electrostatic attraction between hydrogen atoms bonded to small, strongly electronegative atoms (N, O, and F).
• The bonding occurs through the lone pair of electrons on the electronegative atoms.
• Example: HF, H₂O, etc.

2 Types of Hydrogen bonding:- Intermolecular and Intramolecular H-bonding.

• Intermolecular: Hydrogen bond formed between 2 molecules.
• Intramolecular: Hydrogen bond formed between two different atoms of the same molecule.
• Intermolecular Hydrogen bonding is stronger than van der waals' forces. 

The essential requirement of Hydrogen bonding:

1. An H atom must be directly bonded to a highly electronegative atom.

2. Lone pair of electrons must be present on the electronegative atom.

Factors affecting Hydrogen bonding:

1. Association

Due to intermolecular H-bonding, carboxylic acid exists as dimers even in the vapor state.

2. Higher Boiling and Melting point

• Compounds having H-bonding requires larger energy to separate the molecules before they can melt or boil.
• So, the compounds containing H-bonds have high melting and boiling points.

3. Physical state 

Explanation:

The difference in characteristics between NH₃ and PH₃ is given below:-

• Due to the lesser electronegativity of PH₃ molecules, they cannot form H-bonding.
• PH3 can H-bond with water only but not with itself.
• Although PH₃ is larger than NH₃ with greater dispersion forces, NH₃ has a higher polar N--H bond which gives rise to H-bonding.
• Since the strength of the H-bond is greater than the dispersion forces, the boiling point of NH₃ is greater.

The hydrogen bonding in NH₃ is shown below:

Hence, NH3 has a much higher boiling point than PH3 because NH3 forms hydrogen bond.

Concept:

• Hydrogen Bond: hydrogen bond can be defined as the attractive force which binds the hydrogen atom of one molecule with the electronegative atom (F, O or N) of another molecule
• The crystalline form of water is ice.
• At atmospheric pressure, ice crystallises in the hexagonal form, but at very low temperatures it condenses to cubic form. The density of ice is less than that of water. Therefore, an ice cube floats on water. 

Explanation:

Ice

• It is the crystalline form of water.
• Ice has a highly ordered three-dimensional hydrogen-bonded structure.
• Hydrogen bonding gives the ice a rather open type structure with wide holes.
• These holes can hold some other molecules of appropriate size interstitially

Hence from the above figure, we can conclude that the hydrogen in the ice is in the three-dimensional hexagonal structure. Due to the presence of this structure, the density of the ice is less than the water. Therefore the ice floats on the water.

Hence we can conclude that the ice has intermolecular hydrogen bonding.

Additional Information  In the winter season, ice formed on the surface of a lake provides thermal insulation which ensures the survival of the aquatic life. This fact is of great ecological significance.

Option 3 is correct, i.e. When a hydrogen atom is in between the two highly electronegative atoms.

• There are two types of H bond and they are as follows:
  • Intramolecular hydrogen bond.
  • Intermolecular hydrogen bond.

• Intramolecular hydrogen bond:
  • It is formed when a hydrogen atom is in between the two highly electronegative (F, O, N) atoms present within the same molecule. For example, in o-nitrophenol, the hydrogen is in between the two oxygen atoms.
• Intermolecular hydrogen bond:
  • It is formed between two different molecules of the same or different compounds. For example, H-bond in case of HF molecule, alcohol or water molecules, etc.

Concept:

Intermolecular hydrogen bonding: 

• This type of bonding mainly occurs between two or more same or different molecules when they combine to form a dimer or polymer respectively and leads to a phenomenon known as an association.
• Such a type of hydrogen bonding increases the boiling point of the compound and also its solubility in water. 

Intramolecular hydrogen bonding: 

• This type of bonding occurs within two atoms of the same molecule and leads to a phenomenon known as chelation.
• This type of hydrogen bonding frequently occurs in organic compounds and results in the cyclization (six or five-membered ring) of the molecule. 

Explanation:

• o-nitrophenol has intramolecular hydrogen bonding so it is more volatile.
• So, the statement I is true.
• The lowest melting point of o-isomer is due to intramolecular hydrogen bonding whereas meta and para isomers possess intermolecular hydrogen bonding and thus, they have higher melting points. 
• Thus statement II is false.​

Correct Answer: (3)

The correct answer is White Hydrogen.

Key Points

• White hydrogen: Produced from carbon-free nuclear energy.
• Clean and sustainable: No carbon dioxide emissions during production.
• Generated via electrolysis or thermochemical processes using nuclear power.
• Aiming to decarbonize industries and achieve carbon neutrality. 

Additional Information

• Yellow hydrogen:
  • Produced from natural gas through steam methane reforming, emits carbon dioxide.
• Pink hydrogen:
  • Produced through electrolysis powered by renewable energy sources, clean and sustainable.
• Black hydrogen:
  • Produced from coal gasification or steam methane reforming without carbon capture.

The correct answer is option 2.

Concept:

Hydrogen bonding:

• Hydrogen bonding is a special type of interaction that occurs between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.
• It is a special type of dipole-dipole interaction.
• Although H-bond is very weak but compounds having H-bond have high melting and boiling point.

There are two types of H-bonding -

1. Intermolecular H-bonding
2. Intramolecular H-bonding

→ Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen. 

Explanation:

The hydrogen bond is a special type of bond between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.

→ Condition for H-Bonding :

Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen.

∴ only F, O, and N are such atoms that can make an H-bond with the hydrogen of other molecules.

In the given compounds HCl, H2O, HI, and H2S only H2O can form H-bond because Cl, S, and I are large size atoms and cannot form H-bond.

∴ Only H2O will form H-bond 

• Intermolecular H-bonding is there in the water.
• Each H2O can make four H-bonds. Two with O-atom and two with H-atom.
• Each H2O molecule is tetrahedrally linked to the four other H2O molecules.

Conclusion:

Therefore, H-bonding will be strongest in H2O.

Hence, the correct answer is option 2.

Concept:

Hydrogen bonding:

• Hydrogen bonding is a special type of interaction that occurs between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.
• It is a special type of dipole-dipole interaction.
• Although H-bond is very weak but compounds having H-bond have high melting and boiling point.

There are two types of H-bonding -

1. Intermolecular H-bonding
2. Intramolecular H-bonding

→ Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen. 

Explanation:

The hydrogen bond is a special type of bond between a hydrogen atom bonded covalently to an electronegative atom and another highly electronegative atom in the vicinity of this hydrogen.

→ Condition for H-Bonding :

Only small size and highly electronegative atoms are capable of forming H-bond with Hydrogen.

∴ only F, O, and N are such atoms that can make an H-bond with the hydrogen of other molecules.

In the given compounds HCl, H2O, HI, and H2S only H2O can form H-bond because Cl, S, and I are large size atoms and cannot form H-bond.

∴ Only H₂O will form H-bond 

• Intermolecular H-bonding is there in the water.
• Each H₂O can make four H-bonds. Two with O-atom and two with H-atom.
• Each H₂O molecule is tetrahedrally linked to the four other H₂O molecules.

Conclusion:

Therefore, H-bonding will be strongest in H₂O.

Hence, the correct answer is option 2.

Concept:

Hydrogen bonding:

• It is the electrostatic attraction between hydrogen atoms bonded to small, strongly electronegative atoms (N, O, and F).
• The bonding occurs through the lone pair of electrons on the electronegative atoms.
• Example: HF, H₂O, etc.

2 Types of Hydrogen bonding:- Intermolecular and Intramolecular H-bonding.

• Intermolecular: Hydrogen bond formed between 2 molecules.
• Intramolecular: Hydrogen bond formed between two different atoms of the same molecule.
• Intermolecular Hydrogen bonding is stronger than van der waals' forces. 

The essential requirement of Hydrogen bonding:

1. An H atom must be directly bonded to a highly electronegative atom.

2. Lone pair of electrons must be present on the electronegative atom.

Factors affecting Hydrogen bonding:

1. Association

Due to intermolecular H-bonding, carboxylic acid exists as dimers even in the vapor state.

2. Higher Boiling and Melting point

• Compounds having H-bonding requires larger energy to separate the molecules before they can melt or boil.
• So, the compounds containing H-bonds have high melting and boiling points.

3. Physical state 

Explanation:

The difference in characteristics between NH₃ and PH₃ is given below:-

• Due to the lesser electronegativity of PH₃ molecules, they cannot form H-bonding.
• PH3 can H-bond with water only but not with itself.
• Although PH₃ is larger than NH₃ with greater dispersion forces, NH₃ has a higher polar N--H bond which gives rise to H-bonding.
• Since the strength of the H-bond is greater than the dispersion forces, the boiling point of NH₃ is greater.

The hydrogen bonding in NH₃ is shown below:

Hence, NH3 has a much higher boiling point than PH3 because NH3 forms hydrogen bond.