Basic Engineering Chemistry Questions and Answers focuses on “Intermolecular Forces”.
1. Which of the following is a microscopic property?
a) Reactivity
b) Inter-molecular force
c) Boiling point
d) Kinetic energy
Answer: b
Clarification: Inter-molecular force is a microscopic property and all others are the macroscopic property. A macroscopic property describes the characteristics or behaviour of a sample which is large enough to see, handle, manipulate, weigh, etc. A microscopic property describes the behaviour of a much smaller sample of matter, an atom or molecule for instance.
2. Which of the following has the highest bond dissociation energy?
a) Covalent bond
b) Vander Waals forces
c) Dipole-dipole
d) Hydrogen bond
Answer: a
Clarification: Covalent Bond has the highest dissociation energy (400 kJ/mol) among the following options. Vander Waal’s forces are the weakest among the following.
3. The strength of Vander Waals forces depends upon ___________
a) Size of the molecule
b) Molecular structure
c) Number of electrons present in the molecule
d) All of the mentioned
Answer: d
Clarification: The strength of Vander Waals forces depends upon the size of the molecule, molecular structure and the number of electrons present in the molecule.
4. Arrange the following molecules in the order of increasing boiling point.
a) I2 < Br2 < Cl2 < F2
b) F2 < Cl2 < Br2 < I2
c) F2 < Br2 < Cl2 < I2
d) Cl2 < F2 < I2 < Br2
Answer: b
Clarification: The correct order of boiling point is F2 < Cl2 < Br2 < I2.
It is due to the highest electronegativity of fluorine atom.
5. Hydrogen bonding is maximum in ___________
a) Diethyl ether
b) Ethyl chloride
c) Ethanol
d) Triethylamine
Answer: c
Clarification: Hydrogen bonding is maximum in Ethanol. It is a volatile, flammable, colorless liquid with a slight chemical odor. It is used as an antiseptic, a solvent, a fuel, and due to its low freezing point, the active fluid in many alcohol thermometers.
6. Which of the following is not a necessary condition for the formation of intra-molecular hydrogen bonding?
a) A 5 or 6-membered ring should be formed
b) The ring should be planar
c) There should be minimum strain during the ring closure
d) There should be maximum strain during the ring closure
Answer: d
Clarification: The necessary conditions for the formation of intra-molecular hydrogen bonding are: 5 or 6-membered ring should be formed, the ring should be planar and there should be minimum strain during the ring closure.
7. Which of the following is the consequence of hydrogen bonding?
a) Abnormal boiling point
b) Solubility and Viscosity
c) Azeotropic behavior
d) All of the mentioned
Answer: d
Clarification: The consequences of hydrogen bonding are: Abnormal boiling point, solubility, viscosity and azeotropic behavior.
8. O-nitrophenol is more volatile than p-nitrophenol due to ___________
a) Inductive effect
b) Electromeric effect
c) Inter-molecular hydrogen bonding in O-nitrophenol
d) Intra-molecular hydrogen bonding in O-nitrophenol
Answer: d
Clarification: O-nitrophenol is more volatile than p-nitrophenol due to Intra-molecular hydrogen bonding in O-nitrophenol. Intra-molecular hydrogen bonding occurs within different parts of a single molecule.
9. Which of the following possess lowest energy?
a) NO
b) O2
c) N2
d) CO
Answer: c
Clarification: N2 possesses the lowest bond energy among the following options.
10. At what temperature does the water molecules contract?
a) At 00C
b) Below 00C
c) At 40C
d) Between 00C and 40C
Answer: d
Clarification: Water contracts when heated between 00C and 40C. In this range of temperature, all the water molecules breaks down to change its state.
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