APSC 131 EXAM QUESTIONS WITH
100% CORRECT ANSWERS | LATEST
VERSION 2025/2026.
State the Aufbau principle - ANS In the ground state of an atom or ion, electron fill atomic
orbitals in the lowest available energy levels before occupying higher energy levels.
"Aufbau" in German means "building."
Hund's Rule - ANS Every orbital in a subshell is singly occupied with one electron before any
one orbital is doubly occupied.
Think of "Empty Bus Seat."
What is the Heisenberg principle? - ANS The principle states that it is impossible to
determine the exact position or momentum of an electron with high precision.
State the Pauli Exclusion principle. - ANS No two electrons in the same atom can have the
same four quantum numbers.
What is electron affinity? - ANS the energy change that occurs when an electron is acquired
by a neutral atom
Covalent network solids - ANS Held together by an extended network of covalent bonds.
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, State the colligative properties of a solution. - ANS - freezing point depression
- boiling point elevation
- vapour pressure lowering
- osmotic pressure
What is an azeotrope? - ANS An azeotrope is a mixture of two or more liquids in such a way
that it cannot be altered by simple distillation alone. (constant boiling mixtures no change on
boiling)
What is volatile? - ANS Easily evaporated at normal temperatures.
What is the triple point? - ANS the temperature and pressure at which the solid, liquid, and
vapor phases of a pure substance can coexist in equilibrium.
What is the eutectic point? - ANS The point where the horizontal and slope line meet.
What is a coordination number of an atom? - ANS A coordination number of an atom is the
number of other atoms that a certain atom is in direct contact with.
For a simple cubic structure, what is the coordination number? - ANS 6
How many atoms per unit cell are in a simple cubic? - ANS 1 atom
8 atoms (corners) x 1/8 (fraction in unit cell) = 1 atom
How many atoms per unit cell are in a body centered cubic? - ANS 2 atoms
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
100% CORRECT ANSWERS | LATEST
VERSION 2025/2026.
State the Aufbau principle - ANS In the ground state of an atom or ion, electron fill atomic
orbitals in the lowest available energy levels before occupying higher energy levels.
"Aufbau" in German means "building."
Hund's Rule - ANS Every orbital in a subshell is singly occupied with one electron before any
one orbital is doubly occupied.
Think of "Empty Bus Seat."
What is the Heisenberg principle? - ANS The principle states that it is impossible to
determine the exact position or momentum of an electron with high precision.
State the Pauli Exclusion principle. - ANS No two electrons in the same atom can have the
same four quantum numbers.
What is electron affinity? - ANS the energy change that occurs when an electron is acquired
by a neutral atom
Covalent network solids - ANS Held together by an extended network of covalent bonds.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, State the colligative properties of a solution. - ANS - freezing point depression
- boiling point elevation
- vapour pressure lowering
- osmotic pressure
What is an azeotrope? - ANS An azeotrope is a mixture of two or more liquids in such a way
that it cannot be altered by simple distillation alone. (constant boiling mixtures no change on
boiling)
What is volatile? - ANS Easily evaporated at normal temperatures.
What is the triple point? - ANS the temperature and pressure at which the solid, liquid, and
vapor phases of a pure substance can coexist in equilibrium.
What is the eutectic point? - ANS The point where the horizontal and slope line meet.
What is a coordination number of an atom? - ANS A coordination number of an atom is the
number of other atoms that a certain atom is in direct contact with.
For a simple cubic structure, what is the coordination number? - ANS 6
How many atoms per unit cell are in a simple cubic? - ANS 1 atom
8 atoms (corners) x 1/8 (fraction in unit cell) = 1 atom
How many atoms per unit cell are in a body centered cubic? - ANS 2 atoms
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
