CHEM MIDTERM 3 | FROM QUESTION TO PERFECTION|
STUDY WITH CONFIDENCE!
Course Code:
Course Title:
Programme:
Academic Year: 2026/2027
Duration: 2 Hours
Total Marks: 70%
Candidate Instructions:
1) Write your Registration Number on every answer booklet used.
2) Answer ALL questions in Section A and ANY TWO (2) questions in Section B.
3) Read each question carefully before answering.
4) Begin each question on a new page.
5) The marks for each question are indicated in brackets.
6) This paper consists of several printed pages, including this page.
7) Ensure your copy is complete before the examination begins.
8) Unauthorized materials and communication with other candidates are not permitted.
Turn Over.
APPHIA – Crafted with Care and Precision for Academic Excellence.
1
, molecular orbitals are defined with respect to Answer: all the nuclei in the molecule
MOs are obtained from Answer: an analysis of the total wave function describing the F2
molecule in its lowest energy state
the linear combination of atomic orbitals (LCAO) method starts from the premise that Answer:
each MO can be represented mathematically as a linear combination of all AOs
Total number of MOs is equal to the Answer: total number of AOs
MOs can be classified as Answer: bonding, antibonding, or nonbonding
bonding orbitals will have Answer: electron density between the nuclei
antibonding orbitals will have Answer: a node between the nuclei
nonbonding orbitals will typically consist of Answer: AOs isolated on one or more atoms and
neither add to nor detract from bond formation
s orbitals contain Answer: one antibonding sigma and one bonding sigma
p orbitals contain Answer: one antibonding sigma and one bonding sigma, two antibonding pi
and two bonding pi
Max number of electrons per MO Answer: two
If there are two electrons in one MO, they must have Answer: opposite spins
Pauli exclusion principle Answer: An atomic orbital may describe at most two electrons, each
with opposite spin direction
hund's rule Answer: states that single electrons with the same spin must occupy each equal-
energy orbital before additional electrons with opposite spins can occupy the same orbitals
The molecular orbital resulting from the addition of the 1s orbitals (1sA+1sB) is Answer: a
bonding MO
The molecular orbital resulting from the subtraction of the 1s orbitals (1sA−1sB) is Answer: an
antibonding molecular orbital
The σ1s* is ______ in energy than the 1s atomic orbital. Answer: higher
This bonding molecular orbital is given the label σ1s and is _______ in energy than the 1s
atomic orbitals. Answer: lower
a stable molecular species has ______ electrons in bonding orbitals than in antibonding orbitals
Answer: more
if the excess of bonding over antibonding electrons is two, this corresponds to Answer: a single
covalent bond in lewis theory
APPHIA – Crafted with Care and Precision for Academic Excellence.
2
STUDY WITH CONFIDENCE!
Course Code:
Course Title:
Programme:
Academic Year: 2026/2027
Duration: 2 Hours
Total Marks: 70%
Candidate Instructions:
1) Write your Registration Number on every answer booklet used.
2) Answer ALL questions in Section A and ANY TWO (2) questions in Section B.
3) Read each question carefully before answering.
4) Begin each question on a new page.
5) The marks for each question are indicated in brackets.
6) This paper consists of several printed pages, including this page.
7) Ensure your copy is complete before the examination begins.
8) Unauthorized materials and communication with other candidates are not permitted.
Turn Over.
APPHIA – Crafted with Care and Precision for Academic Excellence.
1
, molecular orbitals are defined with respect to Answer: all the nuclei in the molecule
MOs are obtained from Answer: an analysis of the total wave function describing the F2
molecule in its lowest energy state
the linear combination of atomic orbitals (LCAO) method starts from the premise that Answer:
each MO can be represented mathematically as a linear combination of all AOs
Total number of MOs is equal to the Answer: total number of AOs
MOs can be classified as Answer: bonding, antibonding, or nonbonding
bonding orbitals will have Answer: electron density between the nuclei
antibonding orbitals will have Answer: a node between the nuclei
nonbonding orbitals will typically consist of Answer: AOs isolated on one or more atoms and
neither add to nor detract from bond formation
s orbitals contain Answer: one antibonding sigma and one bonding sigma
p orbitals contain Answer: one antibonding sigma and one bonding sigma, two antibonding pi
and two bonding pi
Max number of electrons per MO Answer: two
If there are two electrons in one MO, they must have Answer: opposite spins
Pauli exclusion principle Answer: An atomic orbital may describe at most two electrons, each
with opposite spin direction
hund's rule Answer: states that single electrons with the same spin must occupy each equal-
energy orbital before additional electrons with opposite spins can occupy the same orbitals
The molecular orbital resulting from the addition of the 1s orbitals (1sA+1sB) is Answer: a
bonding MO
The molecular orbital resulting from the subtraction of the 1s orbitals (1sA−1sB) is Answer: an
antibonding molecular orbital
The σ1s* is ______ in energy than the 1s atomic orbital. Answer: higher
This bonding molecular orbital is given the label σ1s and is _______ in energy than the 1s
atomic orbitals. Answer: lower
a stable molecular species has ______ electrons in bonding orbitals than in antibonding orbitals
Answer: more
if the excess of bonding over antibonding electrons is two, this corresponds to Answer: a single
covalent bond in lewis theory
APPHIA – Crafted with Care and Precision for Academic Excellence.
2
