Military Nursing Service (MNS) Entrance Chemistry Flashcards

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.

1. Define order and molecularity of a reaction.

   Order is the sum of powers of concentration terms in the experimental rate law (can be zero/fractional). Molecularity is the number of reacting species in an elementary step (always a whole number ≥1).

2. What is activation energy?

   The minimum energy that reactant molecules must possess (above their average energy) to undergo a successful reaction; the energy barrier between reactants and products.

3. Define the modern periodic law.

   The physical and chemical properties of elements are a periodic function of their atomic numbers.

4. How do atomic radius and ionization energy vary across a period and down a group?

   Across a period (left to right): atomic radius decreases, ionization energy increases. Down a group: atomic radius increases, ionization energy decreases.

5. Define electronegativity and name the most electronegative element.

   Electronegativity is the tendency of an atom to attract a shared pair of electrons toward itself in a bond. Fluorine is the most electronegative element.

6. What are the four blocks of the periodic table based on?

   Based on the subshell in which the differentiating (last) electron enters: s-block, p-block, d-block (transition), and f-block (inner transition).

7. State the octet rule.

   Atoms tend to gain, lose, or share electrons to achieve a stable configuration of eight electrons in their valence shell (a noble gas configuration).

8. Compare ionic and covalent bonds.

   Ionic bonds form by transfer of electrons between metal and non-metal (electrostatic attraction, high m.p., conduct when molten/aqueous). Covalent bonds form by sharing electrons between non-metals (lower m.p., usually poor conductors).

9. What is hybridization and give the geometry for sp, sp², sp³?

   Hybridization is the mixing of atomic orbitals to form equivalent hybrid orbitals. sp → linear (180°); sp² → trigonal planar (120°); sp³ → tetrahedral (109.5°).

10. What does VSEPR theory predict?

    Valence Shell Electron Pair Repulsion theory: electron pairs around a central atom arrange to minimize repulsion, determining molecular geometry (lone pair–lone pair > lone pair–bond pair > bond pair–bond pair repulsion).

11. Why are alkali metals (s-block Group 1) highly reactive?

    They have a single loosely held valence electron with low ionization energy, so they readily lose it to form +1 ions; reactivity increases down the group.

12. What are the diagonal relationship pairs in the s and p blocks?

    Li–Mg, Be–Al, and B–Si show diagonal relationships due to similar charge/radius ratio (and similar polarizing power).

13. Give two characteristic properties of transition (d-block) elements.

    They show variable oxidation states and form coloured ions/compounds (due to d-d electron transitions); they also act as catalysts and form complex ions.

14. What is the lanthanide contraction and one of its consequences?

    The steady decrease in size of lanthanide ions/atoms with increasing atomic number due to poor shielding by 4f electrons. Consequence: second and third transition series elements (e.g. Zr/Hf) have nearly identical sizes.

15. Define metallurgy and name its three broad stages.

    Metallurgy is the science of extracting metals from their ores and refining them. Stages: (1) concentration/enrichment of ore, (2) extraction of crude metal (reduction), (3) refining/purification.

16. What is the role of a flux in metallurgy?

    A flux combines with the infusible gangue (impurities) to form a fusible, easily removable slag (e.g. CaO + SiO₂ → CaSiO₃).

17. Name the methods used to concentrate sulphide and oxide ores.

    Sulphide ores: froth flotation. Oxide/magnetic ores: magnetic separation; soluble impurities removed by leaching; lighter gangue by hydraulic (gravity) separation.

18. Define IUPAC and give the general formula of alkanes, alkenes, and alkynes.

    IUPAC = International Union of Pure and Applied Chemistry (naming system). Alkanes: CₙH₂ₙ₊₂; Alkenes: CₙH₂ₙ; Alkynes: CₙH₂ₙ₋₂.

19. Distinguish between electrophiles and nucleophiles.

    Electrophiles are electron-deficient species that accept an electron pair (e.g. H⁺, NO₂⁺). Nucleophiles are electron-rich species that donate an electron pair (e.g. OH⁻, NH₃, CN⁻).

20. What is Markovnikov's rule?

    In the addition of HX to an unsymmetrical alkene, the hydrogen atom adds to the carbon already bearing more hydrogens, and the halogen to the carbon with fewer hydrogens (forms the more stable carbocation).

21. Name the functional groups: −OH, −CHO, −COOH, −NH₂.

    −OH = alcohol (hydroxyl); −CHO = aldehyde; −COOH = carboxylic acid (carboxyl); −NH₂ = amine (amino group).

22. Classify carbohydrates with one example of each main type.

    Monosaccharides (glucose, fructose), disaccharides (sucrose, maltose, lactose), and polysaccharides (starch, cellulose, glycogen).

23. What causes the greenhouse effect and name two greenhouse gases?

    Trapping of infrared (heat) radiation by atmospheric gases, raising Earth's temperature. Greenhouse gases include CO₂, CH₄, water vapour, N₂O, and CFCs.

24. Distinguish between adsorption and absorption in surface chemistry.

    Adsorption is the accumulation of a substance only at the surface (a surface phenomenon). Absorption is the uniform distribution of a substance throughout the bulk of another (a bulk phenomenon).

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