NUMS — Medical & Dental Entry Test
Take the NUMS Chemistry — Inorganic and Organic Chemistry (Set 5): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. Which of these oxides reacts with both dilute hydrochloric acid and aqueous sodium hydroxide?
Answer: B. Al₂O₃
Explanation: Aluminium oxide is amphoteric: Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O and Al₂O₃ + 2NaOH + 3H₂O → 2Na[Al(OH)₄]. MgO and Na₂O are basic; SiO₂ is acidic and does not react with the dilute acid.
Q2. Magnesium nitrate is strongly heated: 2Mg(NO₃)₂ → 2MgO + 4NO₂ + O₂. What total volume of gases is produced at STP from 14.83 g of Mg(NO₃)₂ (M = 148.3 g mol⁻¹)? (molar volume 22.4 L mol⁻¹)
Answer: D. 5.60 L
Explanation: n = 14.83/148.3 = 0.100 mol. Each 2 mol yields 5 mol gas (4NO₂ + O₂), so 0.100 mol gives 0.250 mol gas = 0.250 × 22.4 = 5.60 L.
Q3. When each of the following nitrates is strongly heated, which one gives brown fumes of nitrogen dioxide?
Answer: B. LiNO₃
Explanation: Lithium's small, highly polarising ion makes LiNO₃ decompose like a Group 2 nitrate: 4LiNO₃ → 2Li₂O + 4NO₂ + O₂. The other nitrates stop at the nitrite, giving only O₂.
Q4. Chlorine gas is passed into hot, concentrated sodium hydroxide solution: 3Cl₂ + 6NaOH → 5NaCl + NaClO₃ + 3H₂O. What are the oxidation numbers of the chlorine in the two chlorine-containing products NaCl and NaClO₃?
Answer: B. −1 and +5
Explanation: Chlorine disproportionates. In NaCl it is reduced to −1; in NaClO₃ (Na +1, O −2 × 3) it is +5. (Cold dilute NaOH gives NaClO, with +1.)
Q5. Potassium permanganate (M = 158.0 g mol⁻¹) is reduced to MnO₂ in neutral solution. What is its equivalent mass in this reaction?
Answer: A. 52.7
Explanation: MnO₄⁻ + 2H₂O + 3e⁻ → MnO₂ + 4OH⁻: Mn changes from +7 to +4, so 3 electrons per formula unit. Equivalent mass = 158.0/3 = 52.7. (In acid, 5 electrons give 31.6.)
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Q6. Two ionisation isomers have the formulae [Co(NH₃)₅Br]SO₄ and [Co(NH₃)₅SO₄]Br. Which statement distinguishes them?
Q7. How many stereoisomers (counting enantiomers separately) exist for the octahedral complex ion [Co(en)₂Cl₂]⁺, where en is the symmetrical bidentate ligand ethane-1,2-diamine?
Q8. How many unpaired electrons are in the octahedral complexes [CoF₆]³⁻ (weak-field F⁻) and [Co(NH₃)₆]³⁺ (strong-field NH₃) respectively?
Q9. In the Ostwald process, NH₃ is oxidised to HNO₃ overall as NH₃ → HNO₃ (1 : 1 on a mole basis). What mass of NH₃ (M = 17.03 g mol⁻¹) is needed to make 6.30 kg of HNO₃ (M = 63.0 g mol⁻¹) if the overall yield is 80.0%?
Q10. In the contact process, all the sulphur in 1.00 kg of sulphur (S = 32.06 g mol⁻¹) is converted into sulphuric acid (M = 98.08 g mol⁻¹). What mass of pure H₂SO₄ forms?
Q11. A hydrogen peroxide solution labelled '10 volume' releases 10 mL of O₂ at STP from each 1 mL on decomposition (2H₂O₂ → 2H₂O + O₂). What is its approximate strength in grams of H₂O₂ per 100 mL? (M = 34.0 g mol⁻¹; molar volume 22.4 L mol⁻¹)
Q12. Among BF₃, BCl₃ and BBr₃, which is the strongest Lewis acid toward a base like NH₃?
Q13. Calcium hydride (M = 42.1 g mol⁻¹) reacts with water: CaH₂ + 2H₂O → Ca(OH)₂ + 2H₂. What volume of H₂ is produced at STP by 4.21 g of CaH₂? (molar volume 22.4 L mol⁻¹)
Q14. What is the IUPAC name of CH₃COCH₂CH₂COOH?
Q15. How many structural isomers (counting alcohols and ethers, but not stereoisomers) have the molecular formula C₄H₁₀O?
Q16. How many stereoisomers does 2,3-dichlorobutane have?
Q17. 2-Methylbut-2-ene is treated with ozone and the ozonide is then reduced with zinc and water. Which products form?
Q18. Which reagent could be used to distinguish but-1-yne from but-2-yne?
Q19. Toluene is treated with chlorine (Cl₂). Under which condition is the major product benzyl chloride, C₆H₅CH₂Cl?
Q20. Ethanol is heated with excess concentrated sulphuric acid at 140 °C (alcohol in excess, acid limiting) versus 170 °C (acid in excess). What are the main products at 140 °C and 170 °C respectively?
Q21. Which of these organic compounds dissolves in aqueous NaOH but does NOT react with aqueous NaHCO₃?
Q22. Which of these carbonyl compounds cannot undergo aldol condensation with dilute NaOH?
Q23. Propanoic acid is warmed with bromine and a little red phosphorus, then water is added. What is the main organic product?
Q24. Ethyl ethanoate (M = 88.1 g mol⁻¹) is hydrolysed completely by excess NaOH: CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH. What mass of sodium ethanoate (M = 82.0 g mol⁻¹) forms from 8.81 g of the ester?
Q25. Which compound gives a foul-smelling isocyanide (carbylamine) when warmed with chloroform and alcoholic KOH?
Q26. Three different amino acids X, Y and Z are each used exactly once to build a tripeptide. How many different tripeptides (different sequences) are possible?
Q27. How many stereoisomers does open-chain glucose, an aldohexose with four different chiral carbons, have in total?
Q28. A sample of poly(vinyl chloride), (CH₂CHCl)ₙ, has an average molar mass of 1.25 × 10⁵ g mol⁻¹. What is the average number of monomer units per chain? (C = 12.0, H = 1.0, Cl = 35.5)
Q29. Triolein (M = 885 g mol⁻¹) contains three C=C bonds. What volume of H₂ at STP is needed to fully hydrogenate 88.5 g of it (Ni catalyst)? (molar volume 22.4 L mol⁻¹)
Q30. A mixture of bromomethane and bromoethane is treated with sodium metal in dry ether (Wurtz reaction). Which set of alkanes forms?