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NUMS Entry Test Chemistry Flashcards
51 question-and-answer cards covering Chemistry as it is examined in NUMS Entry Test. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Chemistry deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
Define hybridization.
The mixing of atomic orbitals of similar energy to form an equal number of new equivalent hybrid orbitals used in bonding.
Give the hybridization, shape and bond angle for sp, sp2 and sp3 carbon.
sp: linear, 180 degrees; sp2: trigonal planar, 120 degrees; sp3: tetrahedral, 109.5 degrees.
What are the shapes of water and ammonia molecules and why do their angles differ from 109.5?
Water is bent/angular (104.5 degrees) and ammonia is pyramidal (107 degrees). Lone pairs repel more strongly than bonding pairs, compressing the bond angles below the tetrahedral 109.5 degrees.
Define bond energy.
The average energy required to break one mole of a particular bond in the gaseous state, breaking it into gaseous atoms. It is always positive (endothermic).
What determines whether a covalent bond is polar?
A difference in electronegativity between the bonded atoms. Unequal electron sharing creates partial charges and a bond dipole; larger electronegativity difference means greater polarity.
Why is CO2 nonpolar despite having polar bonds?
CO2 is linear and symmetric, so the two C=O bond dipoles are equal and opposite and cancel out, giving zero net dipole moment.
List the three main types of intermolecular forces in increasing strength.
London dispersion (induced dipole) forces < dipole-dipole forces < hydrogen bonding.
What is hydrogen bonding and which atoms enable it?
A strong dipole-dipole attraction between a hydrogen atom bonded to a highly electronegative atom (F, O or N) and a lone pair on F, O or N of a neighboring molecule.
State Boyle's law.
At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure (PV = constant).
State Charles's law.
At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute (Kelvin) temperature (V/T = constant).
Write the ideal gas equation and define its terms.
PV = nRT, where P = pressure, V = volume, n = moles, R = universal gas constant (8.314 J/mol K or 0.0821 atm dm3/mol K), T = absolute temperature in Kelvin.
State Avogadro's law.
Equal volumes of all gases at the same temperature and pressure contain an equal number of molecules.
State Graham's law of diffusion.
At constant temperature and pressure, the rate of diffusion of a gas is inversely proportional to the square root of its density (or molar mass): rate proportional to 1/sqrt(M).
Define vapor pressure and how it relates to boiling point.
Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature. A liquid boils when its vapor pressure equals the external (atmospheric) pressure.
How do surface tension and viscosity of a liquid change with increasing temperature?
Both surface tension and viscosity decrease as temperature increases, because higher kinetic energy weakens intermolecular attractions.
What is the difference between crystalline and amorphous solids?
Crystalline solids have a regular, long-range ordered arrangement of particles and sharp melting points. Amorphous solids lack long-range order, behave like supercooled liquids, and soften over a range of temperatures (e.g., glass).
What is a unit cell?
The smallest repeating structural unit of a crystal lattice that, when repeated in three dimensions, generates the entire crystal.
How many atoms are contained in a body-centered cubic (BCC) unit cell?
2 atoms: 8 corner atoms x 1/8 each (= 1) plus 1 atom fully inside the body center.
What characterizes a reversible reaction and dynamic equilibrium?
A reversible reaction proceeds in both forward and backward directions. At dynamic equilibrium the forward and reverse reaction rates are equal, so the concentrations of reactants and products remain constant.
Write the equilibrium constant expression (Kc) for aA + bB <=> cC + dD.
Kc = ([C]^c [D]^d) / ([A]^a [B]^b), where concentrations are equilibrium molar concentrations.
State Le Chatelier's principle.
If a system at equilibrium is disturbed by a change in concentration, pressure or temperature, the equilibrium shifts in the direction that opposes (counteracts) the change.
According to Le Chatelier's principle, how does increasing pressure affect a gaseous equilibrium?
The equilibrium shifts toward the side with the fewer number of gas molecules (lower total moles of gas).
Define solubility product (Ksp) and write it for a salt AB that dissociates into A+ and B-.
Ksp is the equilibrium constant for the dissolution of a sparingly soluble salt in water. For AB <=> A+ + B-, Ksp = [A+][B-].
What is the common ion effect?
The decrease in solubility of a sparingly soluble salt when a soluble compound providing a common ion is added, shifting the dissolution equilibrium backward (Le Chatelier's principle).
What this deck covers
The Chemistry deck follows the NUMS Entry Test Chemistry syllabus — 15 chapters and 47 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 3.4 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 145 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Chemistry flashcards FAQ
How many Chemistry flashcards are in this NUMS Entry Test deck?
51 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these NUMS Entry Test flashcards free?
Yes. The preview here is free to read with no signup, and the full 51-card deck is free inside the Examius app.
What do the Chemistry cards cover?
They follow the NUMS Entry Test Chemistry syllabus — 15 chapters and 47 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.