Engineering Chemistry MCQ (Fission of Covalent Bond)

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Engineering Chemistry MCQ (Fission of Covalent Bond)

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1. A covalent bond between two atoms may be broken in different ways depending upon __________
a) Nature of given organic compound
b) Nature of attacking reagent
c) Reaction conditions
d) All of the mentioned
Answer: d
Explanation: A covalent bond between two atoms may be broken in different ways
depending upon nature of given organic compound, nature of attacking reagent
and reaction conditions.

2. Select the incorrect statement from the following option.
a) Fission of covalent bond leads to the generation of intermediate organic species
b) They are stable and long-lived
c) The presence of reactive intermediates is confirmed by their detection by spectroscopic methods
d) None of the mentioned
Answer: b
Explanation: The intermediate species are unstable and short-lived. All the other
options are correct. Fission of covalent bond leads to the generation of intermediate
organic species. The presence of reactive intermediates is confirmed by their detection by spectroscopic methods.

3. The breaking of a covalent bond in such a way that each atom separates with one electron of the shared pair is called __________
a) Homolytic fission
b) Heterolytic fission
c) Monolytic fission
d) Morpholytic fission
Answer: a
Explanation: The breaking of a covalent bond in such a way that each atom separates
with one electron of the shared pair is called homolytic fission. Homo refers to same
and in this fission every atom has same number of electrons.

4. The breaking of a covalent bond in such a way that both the electrons of shared pair are carried away by one of atom is called __________
a) Morpholytic fission
b) Monolytic fission
c) Heterolytic fission
d) Homolytic fission
Answer: c
Explanation: The breaking of a covalent bond in such a way that both the electrons
of shared pair are carried away by one of atom is called heterolytic fission. Hetero
refers to different and in this fission every atom has different number of electrons.

5. Heterolytic fission takes place between two atoms of widely different __________
a) Conductivity
b) Viscosity
c) Electronegtivity
d) All of the mentioned
Answer: c
Explanation: Heterolytic fission takes place between two atoms of widely different
electronegativity. The more electronegative atom will not attract the electron as
compared to less electronegative atom.

6. Select the incorrect statement from the following option.
a) Heterolytic fission takes place generally in a polar solvent
b) Heterolytic fission takes place usually at higher temperatures
c) Cations and anions formed are generally carbon-based
d) None of the mentioned
Answer: b
Explanation: Heterolytic fission takes place usually at lower temperatures. All the
other options are correct. Heterolytic fission takes place generally in a polar solvent
and cations and anions formed are generally carbon-based.

7. Which of the following is intermediate organic species based on carbon formed by homolytic fission?
a) Carbenes
b) Carbo-cations
c) Carbanions
d) Free radicals
Answer: d
Explanation: Free radicals are intermediate organic species based on carbon formed
by homolytic fission. Free radicals are different from cations and anions. They do not carry any charge with them.

8. Which of the following is intermediate organic species based on carbon formed by photolysis?
a) Carbenes
b) Carbo-cations
c) Carbanions
d) Free radicals
Answer: a
Explanation: Carbenes are intermediate organic species based on carbon formed by
photolysis. A carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons.

9. Triplet carbene is more stable than singlet carbene.
a) True
b) False
Answer: a
Explanation: Triplet carbene is more stable than singlet carbene. A carbene is a
molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons.

10. The shape of carbanion is __________
a) Linear
b) Trigonal planar
c) Pyramidal
d) Bent
Answer: c
Explanation: The shape of carbanion is pyramidal. A carbanion is an anion in which
carbon has an unshared pair of electrons and bears a negative charge usually with
three substituents for a total of eight valence electrons.