NUMS — Medical & Dental Entry Test

NUMS Chemistry — Inorganic and Organic Chemistry (Set 2)

Take the NUMS Chemistry — Inorganic and Organic Chemistry (Set 2): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer…

What this test covers

30 NUMS Chemistry

Sample questions with answers

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

Q1. The ions Na⁺, Mg²⁺, Al³⁺ and F⁻ all have the same electronic configuration (1s² 2s² 2p⁶). Which of them has the largest radius?
- A. Al³⁺
- B. Na⁺
- C. F⁻ ✓
- D. Mg²⁺
Answer: C. F⁻
Explanation: In an isoelectronic series the ion with the fewest protons (F⁻, 9 protons) attracts the 10 electrons least strongly, so it is largest.
Q2. Beryllium shows a diagonal relationship with aluminium. Which property do they share?
- A. Both react vigorously with cold water
- B. Both form strongly basic hydroxides
- C. Their oxides and hydroxides are amphoteric ✓
- D. Both form only ionic chlorides
Answer: C. Their oxides and hydroxides are amphoteric
Explanation: Be and Al have similar charge-to-size ratios, so BeO/Be(OH)₂ and Al₂O₃/Al(OH)₃ dissolve in both acids and alkalis, and their chlorides are covalent.
Q3. Samples of four Group 2 carbonates are heated side by side in a Bunsen flame. Which one gives off carbon dioxide first, i.e. is least thermally stable?
- A. BaCO₃
- B. MgCO₃ ✓
- C. CaCO₃
- D. SrCO₃
Answer: B. MgCO₃
Explanation: The small Mg²⁺ ion polarises the carbonate ion most strongly, weakening its C–O bonds, so MgCO₃ is the least thermally stable.
Q4. Potassium reacts with cold water much more vigorously than sodium does. What is the main reason?
- A. Potassium has a higher nuclear charge, so it holds electrons more tightly
- B. Potassium has a lower first ionisation energy because its outer electron is further from the nucleus ✓
- C. Potassium is denser than water
- D. Potassium forms a covalent hydroxide
Answer: B. Potassium has a lower first ionisation energy because its outer electron is further from the nucleus
Explanation: Down Group 1 atomic radius and shielding increase, so the single valence electron is lost more easily and reactivity increases.
Q5. Hydrofluoric acid etches glass but, unlike hydrochloric acid, it ionises only slightly in water. Among the four hydrogen halides dissolved in water, which ranks as the weakest acid?
- A. HF ✓
- B. HBr
- C. HCl
- D. HI
Answer: A. HF
Explanation: The H–F bond is very strong and short, so HF ionises only partially in water; acid strength increases HF < HCl < HBr < HI as bond strength falls.

The other 25 questions

Take the timed test (free, no sign-up) to see your score and the answer and explanation for every question.

Q6. Household bleach contains sodium hypochlorite, NaOCl. What is the oxidation state of chlorine in it?
- A. +3
- B. +1
- C. −1
- D. +5
Q7. Manganese is a cofactor for several enzymes. How many unpaired electrons does the Mn²⁺ ion have? (Mn, Z = 25)
- A. 7
- B. 5
- C. 3
- D. 4
Q8. EDTA is given intravenously to treat lead poisoning because it wraps around Pb²⁺ ions and is excreted. How many donor atoms does one EDTA ion use to bind a metal ion?
- A. 6
- B. 1
- C. 2
- D. 4
Q9. Iron is used in the Haber process and vanadium(V) oxide in the Contact process. What property of transition elements mainly makes them good catalysts?
- A. Their very low melting points
- B. Their inability to form complexes
- C. Variable oxidation states and the ability to adsorb reactants on their surfaces
- D. Their completely filled d subshells
Q10. In the Ostwald process for manufacturing nitric acid, ammonia is first oxidised to nitrogen monoxide. Which catalyst is used for this step?
- A. Platinum–rhodium gauze
- B. Nickel
- C. Finely divided iron
- D. Vanadium(V) oxide
Q11. When concentrated sulphuric acid is added to sugar (sucrose), a black spongy mass of carbon forms. Which property of the acid does this show?
- A. Dehydrating agent
- B. Strong base
- C. Reducing agent
- D. Precipitating agent
Q12. What is the IUPAC name of (CH₃)₂CHCH₂OH?
- A. 2-Methylpropan-1-ol
- B. 2-Methylpropan-2-ol
- C. Butan-2-ol
- D. Butan-1-ol
Q13. How many structurally isomeric alcohols have the molecular formula C₄H₁₀O?
- A. 4
- B. 3
- C. 7
- D. 2
Q14. Bromomethane is heated with sodium metal in dry ether. What is the main organic product?
- A. Propane
- B. Methane
- C. Ethane
- D. Methanol
Q15. Ethene is shaken with cold, dilute alkaline KMnO₄ (Baeyer's reagent). The purple colour disappears. What organic product forms?
- A. Ethane-1,2-diol
- B. Ethanoic acid
- C. Ethanol
- D. Ethane
Q16. Which test distinguishes but-1-yne (CH≡C–CH₂CH₃) from but-2-yne (CH₃C≡CCH₃)?
- A. Only but-1-yne decolourises bromine water
- B. But-2-yne gives a silver mirror with Tollens' reagent
- C. Only but-2-yne decolourises bromine water
- D. But-1-yne gives a white precipitate with ammoniacal silver nitrate; but-2-yne does not
Q17. Nitrobenzene undergoes further nitration much more slowly than benzene, and the new group enters mainly at one position. Which description of the –NO₂ group is correct?
- A. Deactivating and meta-directing
- B. Deactivating and ortho/para-directing
- C. Activating and ortho/para-directing
- D. Activating and meta-directing
Q18. Benzene reacts with chloromethane in the presence of anhydrous AlCl₃. What is the product and the name of the reaction?
- A. Chlorobenzene; halogenation
- B. Cyclohexane; hydrogenation
- C. Benzoic acid; oxidation
- D. Methylbenzene; Friedel–Crafts alkylation
Q19. 2-Bromopropane is boiled with concentrated KOH dissolved in ethanol. What is the main organic product?
- A. Propan-1-ol
- B. Propan-2-ol
- C. Propane
- D. Propene
Q20. Methylmagnesium bromide (CH₃MgBr) is reacted with methanal (HCHO) and the product is hydrolysed with dilute acid. What alcohol is formed?
- A. 2-Methylpropan-2-ol
- B. Methanol
- C. Propan-2-ol
- D. Ethanol
Q21. A student warms ethanol with an excess of concentrated H₂SO₄ to 170 °C and collects the gas given off. Which compound is the main product?
- A. Ethene
- B. Ethanal
- C. Ethyl hydrogen sulphate only
- D. Diethyl ether
Q22. Ethanol (M = 46) boils at 78 °C, while its isomer dimethyl ether (M = 46) boils at −24 °C. Why?
- A. Ethanol molecules form hydrogen bonds with one another; dimethyl ether molecules cannot
- B. Ethanol is ionic
- C. Dimethyl ether has a higher molar mass
- D. Dimethyl ether molecules are non-polar
Q23. Bromine water is added to aqueous phenol at room temperature. What is observed?
- A. A purple colour appears
- B. No reaction occurs without a catalyst
- C. A single product, 3-bromophenol, forms slowly
- D. A white precipitate of 2,4,6-tribromophenol forms immediately
Q24. Hydrogen cyanide adds across the C=O bond of ethanal to give a cyanohydrin. What type of reaction is this?
- A. Electrophilic substitution
- B. Electrophilic addition
- C. Free-radical substitution
- D. Nucleophilic addition
Q25. Propanone is reduced with sodium borohydride (NaBH₄). What is the product?
- A. Propanal
- B. Propanoic acid
- C. Propan-2-ol
- D. Propan-1-ol
Q26. Which of these carboxylic acids is the strongest?
- A. ClCH₂COOH
- B. Cl₃CCOOH
- C. CH₃COOH
- D. Cl₂CHCOOH
Q27. An amino acid solution is placed in an electric field at a pH equal to its isoelectric point. What happens?
- A. It decomposes into its elements
- B. It moves to the anode as an anion
- C. It moves to the cathode as a cation
- D. The amino acid does not migrate, because it exists as a neutral zwitterion
Q28. Sucrose does not reduce Fehling's solution, although its component monosaccharides glucose and fructose do. Why?
- A. Sucrose is a polysaccharide
- B. The reducing (anomeric) carbons of both units are used in the glycosidic bond
- C. Sucrose contains a free aldehyde group
- D. Sucrose is insoluble in water
Q29. PVC, used for blood bags and drip tubing, is made by which process and from which monomer?
- A. Addition polymerisation of chloroethene (vinyl chloride)
- B. Condensation polymerisation of chloroethane
- C. Condensation polymerisation of vinyl alcohol
- D. Addition polymerisation of ethene and HCl
Q30. Chlorofluorocarbons (CFCs) damage the stratospheric ozone layer. Which step starts this damage?
- A. CFCs absorb infrared radiation and heat the ozone
- B. UV light breaks C–Cl bonds, releasing chlorine free radicals that destroy ozone in a chain reaction
- C. CFCs react directly with oxygen to form CO₂
- D. Fluorine atoms combine with ozone to form HF