chemistry : class11 Hydrogen Bonding : Melting point : States of Matter: Gases and Liquids MCQ Questions and Answers
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Hydrogen Bonding
MCQ questions and answers.
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MCQ Questions
1. What type of attraction is a hydrogen bond?
A.
A strong covalent bond between two carbon atoms
B.
An attraction involving hydrogen bonded to a highly electronegative atom
C.
An attraction between two metal ions
D.
A bond formed only between noble gases
Correct Answer:
An attraction involving hydrogen bonded to a highly electronegative atom
Explanation:
A hydrogen bond is an intermolecular attraction in which hydrogen bonded to nitrogen, oxygen, or fluorine is attracted to a lone pair on another electronegative atom.
2. Which element commonly forms hydrogen bonds when bonded to hydrogen?
A.
Sodium
B.
Carbon
C.
Oxygen
D.
Chlorine
Correct Answer:
Oxygen
Explanation:
Oxygen is highly electronegative and can form hydrogen bonds when it is bonded to hydrogen, as in water.
3. Why does hydrogen bonding generally increase the melting point of a substance?
A.
It weakens the attraction between molecules
B.
It increases the attraction between molecules
C.
It removes all intermolecular forces
D.
It changes molecules into ions
Correct Answer:
It increases the attraction between molecules
Explanation:
Hydrogen bonding provides an additional strong intermolecular attraction, so more energy is needed to separate molecules during melting.
4. Which substance has hydrogen bonding between its molecules?
A.
Methane, CH4
B.
Water, H2O
C.
Carbon dioxide, CO2
D.
Hydrogen sulfide, H2S
Correct Answer:
Water, H2O
Explanation:
Water molecules contain O–H bonds, allowing hydrogen bonds to form between neighboring water molecules.
5. Which condition is necessary for hydrogen bonding in a molecule?
A.
Hydrogen must be directly bonded to nitrogen, oxygen, or fluorine
B.
Hydrogen must be bonded to a metal
C.
The molecule must contain carbon only
D.
The molecule must be a noble gas
Correct Answer:
Hydrogen must be directly bonded to nitrogen, oxygen, or fluorine
Explanation:
A hydrogen bond is possible when hydrogen is attached to a highly electronegative atom such as nitrogen, oxygen, or fluorine.
6. Which compound is expected to have a relatively high melting point because of hydrogen bonding?
A.
Ethanol, C2H5OH
B.
Ethane, C2H6
C.
Propane, C3H8
D.
Methane, CH4
Correct Answer:
Ethanol, C2H5OH
Explanation:
Ethanol contains an O–H group, so its molecules can form hydrogen bonds, increasing intermolecular attraction and raising its melting point relative to similar non-hydrogen-bonding molecules.
7. In hydrogen bonding, the hydrogen atom is usually partially positive because it is bonded to an atom that is:
A.
Less electronegative
B.
Highly electronegative
C.
A metal
D.
A noble gas
Correct Answer:
Highly electronegative
Explanation:
A highly electronegative atom attracts the shared electrons strongly, leaving the bonded hydrogen partially positive and able to participate in hydrogen bonding.
8. Which pair of molecules can form hydrogen bonds with each other?
A.
H2O and H2O
B.
CH4 and CH4
C.
CO2 and CO2
D.
Cl2 and Cl2
Correct Answer:
H2O and H2O
Explanation:
Water molecules have O–H bonds and lone pairs on oxygen, enabling hydrogen bonds between neighboring water molecules.
9. Compared with a similar molecule that cannot form hydrogen bonds, a hydrogen-bonded substance usually requires what to melt?
A.
Less energy
B.
No energy
C.
More energy
D.
Only light energy
Correct Answer:
More energy
Explanation:
Hydrogen bonds hold molecules together more strongly, so additional energy is needed to overcome these attractions during melting.
10. Which molecule contains an O–H group capable of forming hydrogen bonds?
A.
Methanol, CH3OH
B.
Methane, CH4
C.
Ethene, C2H4
D.
Carbon dioxide, CO2
Correct Answer:
Methanol, CH3OH
Explanation:
Methanol contains an O–H bond, allowing its molecules to form hydrogen bonds with one another.
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