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NUMS — Medical & Dental Entry Test

NUMS Chemistry — Inorganic and Organic Chemistry (Set 4)

Take the NUMS Chemistry — Inorganic and Organic Chemistry (Set 4): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer…

What this test covers

Sample questions with answers

The first 5 questions of this test, with the correct answer and explanation.

  1. Q1. Which of these isoelectronic ions has the largest radius?

    • A. K⁺
    • B. Cl⁻
    • C. Ca²⁺
    • D. S²⁻ ✓

    Answer: D. S²⁻

    Explanation: All have 18 electrons. With the same electron count, the ion with the smallest nuclear charge (Z = 16 for S²⁻) holds the electrons least tightly and is largest.

  2. Q2. For which of these elements is the second ionisation energy the highest?

    • A. Calcium
    • B. Aluminium
    • C. Sodium ✓
    • D. Magnesium

    Answer: C. Sodium

    Explanation: Removing the second electron from Na⁺ means breaking into the stable neon core (2p⁶). Mg, Al and Ca lose their second electron from the valence shell, so their second IE is much lower.

  3. Q3. Which alkali metal forms its normal oxide (M₂O) when burned in excess oxygen?

    • A. Sodium
    • B. Rubidium
    • C. Lithium ✓
    • D. Potassium

    Answer: C. Lithium

    Explanation: Small Li⁺ polarises the large O₂²⁻ and O₂⁻ ions too strongly, so only Li₂O is stable. Na forms mainly Na₂O₂, while K and Rb form superoxides (MO₂).

  4. Q4. Which sulphate has the lowest solubility in water?

    • A. SrSO₄
    • B. CaSO₄
    • C. BaSO₄ ✓
    • D. MgSO₄

    Answer: C. BaSO₄

    Explanation: Sulphate solubility falls down Group 2 because the lattice energy decreases less than the hydration energy. BaSO₄ is virtually insoluble, which is why it is used in barium meals.

  5. Q5. Lead(II) compounds are generally more stable than lead(IV) compounds, and PbO₂ is a strong oxidising agent. Which concept best explains this?

    • A. The inert pair effect ✓
    • B. Hydrogen bonding
    • C. The diagonal relationship
    • D. The lanthanide contraction alone

    Answer: A. The inert pair effect

    Explanation: The 6s² electrons of lead are held tightly (relativistic stabilisation and poor shielding by 4f electrons), so Pb prefers +2. PbO₂ gains electrons readily to form Pb²⁺.

The other 25 questions

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  1. Q6. Chlorine gas is passed into hot, concentrated NaOH solution. What are the main products?

    • A. NaClO and NaClO₃
    • B. NaCl and NaClO₃
    • C. NaCl and NaClO
    • D. NaCl and NaClO₄

  2. Q7. In aqueous solution HI is a strong acid but HF is a weak acid, although fluorine is the most electronegative halogen. What is the main reason?

    • A. Iodine has a higher oxidation state in HI than fluorine has in HF
    • B. HF is a larger molecule than HI so it ionises less
    • C. The H–F bond is much stronger than H–I, so HF ionises far less
    • D. Fluorine is less electronegative than iodine in the molecule

  3. Q8. Which aqueous ion is colourless because it has no d electrons that can be promoted?

    • A. Fe³⁺
    • B. Sc³⁺
    • C. Ni²⁺
    • D. Cu²⁺

  4. Q9. Excess AgNO₃ solution is added to separate solutions, each containing 1 mol of [Co(NH₃)₅Cl]Cl₂ and of [Co(NH₃)₄Cl₂]Cl. What are the moles of AgCl precipitated, in that order?

    • A. 2 mol and 1 mol
    • B. 3 mol and 2 mol
    • C. 2 mol and 2 mol
    • D. 3 mol and 3 mol

  5. Q10. Which complex ion is diamagnetic? (Z of Fe = 26)

    • A. [Fe(H₂O)₆]²⁺
    • B. [Fe(CN)₆]⁴⁻
    • C. [Fe(H₂O)₆]³⁺
    • D. [FeF₆]³⁻

  6. Q11. Copper reacts with dilute and with concentrated nitric acid. Which products are formed?

    • A. NO from dilute acid and NO₂ from concentrated acid
    • B. NO₂ from dilute acid and NO from concentrated acid
    • C. H₂ from both acids
    • D. N₂O from both acids

  7. Q12. In the Solvay process for Na₂CO₃, which substance is the only waste by-product?

    • A. NH₃
    • B. CaCl₂
    • C. CO₂
    • D. NH₄Cl

  8. Q13. Which oxide reacts with both aqueous HCl and aqueous NaOH?

    • A. P₄O₁₀
    • B. CaO
    • C. SiO₂
    • D. Al₂O₃

  9. Q14. White phosphorus (P₄) is far more reactive than red phosphorus. What is the principal reason?

    • A. P₄ is ionic whereas red phosphorus is covalent in nature
    • B. The 60° P–P–P angles in P₄ cause large ring strain
    • C. Red phosphorus has no P–P bonds at all in its structure
    • D. P₄ contains P=P double bonds that are easily broken

  10. Q15. What is the IUPAC name of CH₃–CH(OH)–CH₂–CH(CH₃)–CH₃?

    • A. 1,3-Dimethylbutan-1-ol
    • B. 4-Methylpentan-2-ol
    • C. 2-Methylpentan-4-ol
    • D. Isohexyl alcohol (hexan-2-ol)

  11. Q16. How many alkenes (counting cis and trans isomers separately) have the molecular formula C₄H₈?

    • A. 5
    • B. 2
    • C. 4
    • D. 3

  12. Q17. How many different monochloro products (structural isomers) can form when 2-methylbutane is chlorinated in light?

    • A. 4
    • B. 5
    • C. 2
    • D. 3

  13. Q18. Propene reacts with HBr in the presence of organic peroxide. What is the major product?

    • A. Propan-2-ol
    • B. 1-Bromopropane
    • C. 2-Bromopropane
    • D. 1,2-Dibromopropane

  14. Q19. Ozonolysis followed by reductive work-up of 2-methylbut-2-ene, (CH₃)₂C=CHCH₃, gives which products?

    • A. Ethanal and butanone
    • B. Propanal and propanone
    • C. Propanone and ethanal
    • D. Two molecules of propanone

  15. Q20. Which of these gives a white precipitate with ammoniacal silver nitrate?

    • A. But-2-yne
    • B. But-1-yne
    • C. But-1-ene
    • D. Butane

  16. Q21. Which of the following cannot be oxidised to benzoic acid by hot alkaline KMnO₄?

    • A. tert-Butylbenzene
    • B. Isopropylbenzene (cumene)
    • C. Ethylbenzene
    • D. Toluene

  17. Q22. Which species is aromatic according to Hückel's rule (4n + 2 π electrons, planar and cyclic, fully conjugated)?

    • A. Cyclopentadienyl cation, C₅H₅⁺
    • B. Cyclooctatetraene, C₈H₈ (planar)
    • C. Cyclobutadiene, C₄H₄
    • D. Cyclopentadienyl anion, C₅H₅⁻

  18. Q23. Butan-2-ol is dehydrated by heating with concentrated H₂SO₄. What is the major alkene formed?

    • A. 2-Methylpropene
    • B. But-1-ene
    • C. Butane
    • D. But-2-ene

  19. Q24. Which reagent gives an immediate white precipitate of 2,4,6-tribromophenol when added to aqueous phenol?

    • A. Bromine water
    • B. Tollens' reagent
    • C. Neutral FeCl₃
    • D. Sodium bicarbonate

  20. Q25. Which compound gives a yellow precipitate of iodoform (CHI₃) when warmed with iodine and NaOH?

    • A. Butan-1-ol
    • B. Pentan-3-one
    • C. Propanal
    • D. Butan-2-one

  21. Q26. Which aldehyde cannot undergo the aldol condensation in dilute NaOH?

    • A. Benzaldehyde
    • B. Propanal
    • C. Butanal
    • D. Ethanal

  22. Q27. Which of these is the strongest acid?

    • A. ClCH₂COOH
    • B. CH₃COOH
    • C. FCH₂COOH
    • D. Cl₂CHCOOH

  23. Q28. Which of the following correctly lists the amines in order of increasing basicity in aqueous solution?

    • A. CH₃NH₂ < (CH₃)₂NH < NH₃ < Aniline
    • B. NH₃ < Aniline < CH₃NH₂ < (CH₃)₂NH
    • C. Aniline < NH₃ < CH₃NH₂ < (CH₃)₂NH
    • D. Aniline < (CH₃)₂NH < CH₃NH₂ < NH₃

  24. Q29. How many different tripeptides can be made if three different amino acids are each used exactly once?

    • A. 6
    • B. 3
    • C. 27
    • D. 9

  25. Q30. A single linear nylon-6,6 chain is formed from 10 molecules of hexane-1,6-diamine and 10 molecules of hexanedioic acid joined end to end. How many water molecules are eliminated?

    • A. 10
    • B. 18
    • C. 20
    • D. 19