ECAT — Engineering College Admission Test (UET)

ECAT Chemistry — Transition Elements and Industrial Chemistry (Set 3)

Take the ECAT Chemistry — Transition Elements and Industrial Chemistry (Set 3): 30 multiple-choice questions (40 minutes) with instant scoring and a full…

What this test covers

30 ECAT Chemistry

Sample questions with answers

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

Q1. The spin-only magnetic moment of Fe³⁺ (Z = 26) in Bohr magnetons is closest to:
- A. 5.92 ✓
- B. 4.90
- C. 3.87
- D. 2.83
Answer: A. 5.92
Explanation: Fe³⁺ = 3d⁵: five unpaired electrons; μ = √(n(n+2)) = √35 = 5.92 BM.
Q2. Which of the following aqueous ions is expected to be coloured?
- A. Sc³⁺
- B. Zn²⁺
- C. Ti³⁺ ✓
- D. Cu⁺
Answer: C. Ti³⁺
Explanation: Ti³⁺ is 3d¹ (d–d transition possible); Sc³⁺ is d⁰ and Zn²⁺ and Cu⁺ are d¹⁰.
Q3. The oxidation state of nickel in the carbonyl complex [Ni(CO)₄] is:
- A. +2
- B. +4
- C. 0 ✓
- D. −4
Answer: C. 0
Explanation: CO is a neutral ligand and the complex is neutral, so Ni = 0.
Q4. 0.01 mol of [Co(NH₃)₅Cl]Cl₂ is dissolved in water and excess AgNO₃ is added. The moles of AgCl precipitated are:
- A. 0.00
- B. 0.03
- C. 0.01
- D. 0.02 ✓
Answer: D. 0.02
Explanation: Only the two Cl⁻ outside the coordination sphere are free: 0.02 mol AgCl.
Q5. The effective atomic number (EAN) of iron in K₄[Fe(CN)₆] is:
- A. 34
- B. 26
- C. 36 ✓
- D. 24
Answer: C. 36
Explanation: EAN = Z − oxidation state + 2 × CN = 26 − 2 + 12 = 36, equal to Kr.

The other 25 questions

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Q6. The complex [Pt(NH₃)₂Cl₂] (square planar) exists as:
- A. two geometrical isomers, cis and trans
- B. three structural isomers
- C. a single isomer only
- D. two optical isomers
Q7. The IUPAC name of K₃[Fe(CN)₆] is:
- A. tripotassium hexacyanide ferrate(II)
- B. potassium ferricyanide(II)
- C. potassium hexacyanidoferrate(III)
- D. potassium hexacyanoiron(II)
Q8. Ethylenediamine (en) is a:
- A. tridentate ligand
- B. bidentate ligand
- C. monodentate ligand
- D. hexadentate ligand
Q9. [Fe(CN)₆]⁴⁻ is diamagnetic whereas [Fe(H₂O)₆]²⁺ is paramagnetic because:
- A. CN⁻ is a strong-field ligand, giving a low-spin d⁶ complex with all electrons paired
- B. water has no lone pair available to bond with iron
- C. CN⁻ is a weak-field ligand, so the electrons stay unpaired
- D. iron has different oxidation states in the two complexes
Q10. The colour of many transition metal complexes arises because:
- A. d electrons are promoted between split d levels (d–d transitions) absorbing visible light
- B. electrons are lost from the ligands
- C. the complex absorbs infrared only
- D. s electrons are removed
Q11. In the blast furnace, the slag formed removes the silica impurity of iron ore as:
- A. calcium carbonate
- B. calcium silicate
- C. iron silicate
- D. carbon monoxide
Q12. The main reducing agent in the blast furnace for reducing Fe₂O₃ in the upper and middle zone is:
- A. carbon dioxide
- B. carbon monoxide
- C. hydrogen
- D. silicon
Q13. Rusting of iron is prevented by the attachment of a magnesium block to a ship's hull because:
- A. Mg is less reactive than Fe so it protects the hull
- B. Mg forms a paint-like protective coating on the hull
- C. Mg lowers the temperature of the surrounding sea water
- D. Mg is more easily oxidised than Fe, so it acts as a sacrificial anode
Q14. Galvanised iron (zinc coating) continues to resist rusting even when the coating is scratched because:
- A. the exposed iron is covered by Zn oxide only
- B. Zn forms an alloy with Fe instantly
- C. Zn is less reactive than Fe
- D. Zn is more reactive than Fe and oxidises first (sacrificial protection)
Q15. The colour change when a few drops of NaOH are added to orange potassium dichromate solution is:
- A. orange to green
- B. orange to colourless
- C. orange to yellow
- D. orange to purple
Q16. The oxidation state of chromium in the dichromate ion Cr₂O₇²⁻ is:
- A. +6
- B. +7
- C. +12
- D. +3
Q17. The equivalent mass of KMnO₄ (molar mass 158) in acidic medium (MnO₄⁻ → Mn²⁺) is:
- A. 158
- B. 31.6
- C. 79
- D. 52.7
Q18. The number of electrons gained by MnO₄⁻ when it is reduced in neutral medium to MnO₂ is:
- A. 5
- B. 7
- C. 3
- D. 1
Q19. What amount of KMnO₄ in acidic medium is needed to oxidise 0.1 mol of oxalate ion C₂O₄²⁻ completely to CO₂? (2MnO₄⁻ + 5C₂O₄²⁻ + 16H⁺ → 2Mn²⁺ + 10CO₂ + 8H₂O)
- A. 0.25 mol
- B. 0.02 mol
- C. 0.1 mol
- D. 0.04 mol
Q20. The common catalyst and temperature in the Haber process for ammonia are:
- A. Ni at 150 °C
- B. Pt–Rh gauze at 800 °C
- C. finely divided iron with Mo promoter at about 450 °C
- D. V₂O₅ at 450 °C
Q21. The percentage of nitrogen by mass in urea, CO(NH₂)₂ (C = 12, O = 16, N = 14, H = 1), is:
- A. 23.3%
- B. 35.0%
- C. 46.7%
- D. 28.0%
Q22. The percentage of nitrogen in ammonium sulphate (NH₄)₂SO₄ (N = 14, H = 1, S = 32, O = 16) is closest to:
- A. 10.6%
- B. 21.2%
- C. 28.0%
- D. 42.4%
Q23. Superphosphate of lime is manufactured by treating phosphate rock Ca₃(PO₄)₂ with:
- A. sulphuric acid
- B. hydrochloric acid only
- C. nitric acid only
- D. ammonia
Q24. Gypsum is added to Portland cement clinker in small amounts in order to:
- A. increase the strength after one year
- B. slow the setting of cement
- C. give a pure white colour
- D. increase the ability to colour
Q25. The raw materials used for manufacturing Portland cement are mainly:
- A. limestone and clay
- B. quartz and sodium carbonate
- C. gypsum and coke
- D. bauxite and cryolite
Q26. An octane number of 100 is assigned to:
- A. benzene
- B. n-heptane
- C. n-octane
- D. iso-octane (2,2,4-trimethylpentane)
Q27. Among the petroleum fractions obtained by fractional distillation, the one with the highest boiling range is:
- A. petrol (gasoline)
- B. kerosene
- C. bitumen/residue
- D. LPG
Q28. Normal rainwater has a pH of about 5.6 due to dissolved:
- A. NO₂
- B. CO₂
- C. SO₂
- D. O₃
Q29. Catalytic converters in car exhausts use platinum–rhodium to:
- A. remove lead from petrol
- B. convert CO₂ to O₂
- C. convert CO, NOx and unburnt hydrocarbons to CO₂, N₂ and H₂O
- D. produce more NOx
Q30. The sulphite process of making paper pulp uses:
- A. hydrochloric acid
- B. calcium (or magnesium) bisulphite solution
- C. sodium hydroxide only
- D. chlorine gas only