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🇵🇰 NED Admission Test · flashcards
NED Admission Test Chemistry Flashcards
50 question-and-answer cards covering Chemistry as it is examined in NED Admission 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.
What is a covalent bond, and what is the difference between a polar and a nonpolar covalent bond?
A covalent bond is formed by the sharing of electron pairs between atoms. It is nonpolar when shared equally (between identical or similar-electronegativity atoms) and polar when shared unequally, creating partial charges.
What is a coordinate (dative) covalent bond? Give an example.
A covalent bond in which both shared electrons are donated by the same atom. Example: the bond between NH3 and H+ to form the ammonium ion (NH4+), where nitrogen donates its lone pair.
State the octet rule and give one common exception.
The octet rule states that atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell (a noble-gas configuration). An exception is boron in BF3, which is stable with only six valence electrons.
What is the main postulate of VSEPR theory?
Valence Shell Electron Pair Repulsion theory states that electron pairs (bonding and lone pairs) around a central atom arrange themselves to be as far apart as possible to minimize repulsion, which determines the molecule's shape.
In VSEPR theory, rank the strength of repulsions between lone pairs (lp) and bonding pairs (bp).
Lone pair-lone pair > lone pair-bonding pair > bonding pair-bonding pair. Lone pairs repel more strongly because they are held by only one nucleus and occupy more space.
State the molecular geometry and bond angle for 2, 3, and 4 bonding pairs with no lone pairs on the central atom.
2 pairs: linear, 180 degrees. 3 pairs: trigonal planar, 120 degrees. 4 pairs: tetrahedral, 109.5 degrees.
What are the shapes and bond angles of water (H2O) and ammonia (NH3), and why do they differ from the ideal tetrahedral angle?
H2O is bent/angular (about 104.5 degrees) with 2 lone pairs; NH3 is trigonal pyramidal (about 107 degrees) with 1 lone pair. Lone pair repulsion compresses the bond angle below the ideal 109.5 degrees.
What is the molecular geometry of a molecule with 5 bonding pairs and one with 6 bonding pairs (no lone pairs)?
5 bonding pairs: trigonal bipyramidal (angles 120 and 90 degrees), e.g. PCl5. 6 bonding pairs: octahedral (90 degrees), e.g. SF6.
What is hybridization?
Hybridization is the mixing of atomic orbitals of similar energy (e.g. s and p) on an atom to form an equal number of new, equivalent hybrid orbitals that have suitable geometry for bonding.
State the hybridization, geometry, and bond angle for sp, sp2, and sp3 hybridization.
sp: linear, 180 degrees (2 orbitals). sp2: trigonal planar, 120 degrees (3 orbitals). sp3: tetrahedral, 109.5 degrees (4 orbitals).
What is the hybridization of carbon in methane (CH4), ethene (C2H4), and ethyne (C2H2)?
Methane (CH4): sp3. Ethene (C2H4): sp2 (contains a C=C double bond). Ethyne (C2H2): sp (contains a C-triple-bond-C).
What is the difference between a sigma and a pi bond?
A sigma bond forms by head-on (axial) overlap of orbitals and is stronger. A pi bond forms by sidewise (lateral) overlap of unhybridized p orbitals and is weaker. A double bond = 1 sigma + 1 pi; a triple bond = 1 sigma + 2 pi.
List the three main types of intermolecular forces in order of increasing strength.
London dispersion forces (weakest) < dipole-dipole forces < hydrogen bonding (strongest). All are weaker than covalent or ionic bonds.
What is hydrogen bonding, and which atoms must be involved?
Hydrogen bonding is a strong dipole-dipole attraction between a hydrogen atom covalently bonded to a highly electronegative atom (F, O, or N) and a lone pair on another electronegative atom (F, O, or N).
What are London dispersion forces, and how does their strength depend on molecular size?
London (dispersion) forces are weak attractions arising from temporary instantaneous dipoles in electron clouds. They are present in all molecules and increase with molecular size, mass, and number of electrons (greater polarizability).
Why does water have an unusually high boiling point compared to H2S?
Water molecules form extensive hydrogen bonds (O is highly electronegative), which require much more energy to break, whereas H2S has only weak dipole-dipole and dispersion forces, giving it a much lower boiling point.
State Boyle's Law (equation and conditions).
At constant temperature and fixed amount of gas, the volume of a gas is inversely proportional to its pressure: P x V = constant, or P1V1 = P2V2.
State Charles's Law (equation and conditions).
At constant pressure and fixed amount of gas, the volume of a gas is directly proportional to its absolute (Kelvin) temperature: V/T = constant, or V1/T1 = V2/T2.
Write the ideal gas equation and define each term with SI/standard units.
PV = nRT, where P = pressure, V = volume, n = number of moles, T = absolute temperature (K), and R = the universal gas constant (0.0821 L atm K^-1 mol^-1, or 8.314 J K^-1 mol^-1).
State Avogadro's Law and the molar volume of an ideal gas at STP.
Avogadro's Law: equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. At STP (0 degrees C, 1 atm), one mole of any ideal gas occupies 22.4 litres.
What is vapour pressure, and how does it change with temperature?
Vapour pressure is the pressure exerted by a vapour in equilibrium with its liquid in a closed container at a given temperature. It increases as temperature increases because more molecules have enough energy to escape the liquid.
Define the boiling point of a liquid in terms of vapour pressure.
The boiling point is the temperature at which the vapour pressure of the liquid becomes equal to the external (atmospheric) pressure. At higher altitude, lower atmospheric pressure lowers the boiling point.
What is the difference between a crystalline solid and an amorphous solid? Give one example of each.
A crystalline solid has a regular, repeating long-range ordered arrangement of particles and a sharp melting point (e.g. NaCl, diamond). An amorphous solid has a disordered arrangement, no sharp melting point (e.g. glass, plastic).
Name the four main types of crystalline solids classified by bonding, with an example of each.
Ionic (e.g. NaCl), covalent/network (e.g. diamond), metallic (e.g. copper), and molecular (e.g. solid CO2 / dry ice). They differ in the particles and forces holding the lattice together.
What this deck covers
The Chemistry deck follows the NED Admission Test Chemistry syllabus — 12 chapters and 38 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 4.2 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 185 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 NED Admission Test deck?
50 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these NED Admission Test flashcards free?
Yes. The preview here is free to read with no signup, and the full 50-card deck is free inside the Examius app.
What do the Chemistry cards cover?
They follow the NED Admission Test Chemistry syllabus — 12 chapters and 38 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.