ECAT — Engineering College Admission Test (UET)

ECAT Chemistry — Transition Elements and Industrial Chemistry (Set 1)

Take the ECAT Chemistry — Transition Elements and Industrial Chemistry (Set 1): 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 general valence-shell electronic configuration of d-block (transition) elements is:
- A. ns¹⁻²
- B. (n−2)f¹⁻¹⁴ ns²
- C. (n−1)d¹⁻¹⁰ ns¹⁻² ✓
- D. ns² np¹⁻⁶
Answer: C. (n−1)d¹⁻¹⁰ ns¹⁻²
Explanation: Transition elements fill the (n−1)d subshell while ns holds one or two electrons.
Q2. Which ion is colourless in aqueous solution?
- A. Sc³⁺ ✓
- B. Cu²⁺
- C. Fe³⁺
- D. Ti³⁺
Answer: A. Sc³⁺
Explanation: Sc³⁺ has a 3d⁰ configuration, so no d–d transition is possible; the other ions have partly filled d orbitals.
Q3. The colour of most transition metal complexes is due to:
- A. the presence of unpaired s electrons
- B. emission of X-rays
- C. the high melting points of the metals
- D. d–d electronic transitions absorbing visible light ✓
Answer: D. d–d electronic transitions absorbing visible light
Explanation: Ligands split the d orbitals; electrons absorb visible light to jump between them and the complementary colour is seen.
Q4. The spin-only magnetic moment of Mn²⁺ (Z of Mn = 25) is about:
- A. 1.73 BM
- B. 3.87 BM
- C. 4.90 BM
- D. 5.92 BM ✓
Answer: D. 5.92 BM
Explanation: Mn²⁺ is 3d⁵ with 5 unpaired electrons: μ = √(n(n + 2)) = √35 ≈ 5.92 BM.
Q5. Which element shows the largest number of oxidation states among the 3d series?
- A. Cu
- B. Sc
- C. Zn
- D. Mn ✓
Answer: D. Mn
Explanation: Mn (3d⁵ 4s²) shows every oxidation state from +2 to +7.

The other 25 questions

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Q6. The coordination number and oxidation state of cobalt in [Co(NH₃)₅Cl]Cl₂ are:
- A. 5 and +3
- B. 8 and +3
- C. 6 and +2
- D. 6 and +3
Q7. In the complex [Ni(CO)₄], used in the Mond process for refining nickel, the oxidation state of nickel is:
- A. +2
- B. 0
- C. +4
- D. −4
Q8. Ethylenediamine (H₂N–CH₂–CH₂–NH₂) acts as a ligand that is:
- A. hexadentate
- B. monodentate
- C. tridentate
- D. bidentate
Q9. The complex ion [Cu(NH₃)₄]²⁺ has the geometry:
- A. linear
- B. square planar
- C. octahedral
- D. tetrahedral
Q10. In the blast furnace, limestone is added mainly to:
- A. remove silica impurities as slag (CaSiO₃)
- B. supply carbon to the iron
- C. increase the temperature of the furnace
- D. reduce iron oxide directly
Q11. Which form of iron has the lowest carbon content?
- A. Pig iron
- B. Wrought iron
- C. High-carbon steel
- D. Cast iron
Q12. Stainless steel is an alloy of iron with mainly:
- A. tin and lead
- B. copper and zinc
- C. manganese and silicon only
- D. chromium and nickel
Q13. Galvanizing protects iron from rusting by coating it with:
- A. tin
- B. chromium
- C. copper
- D. zinc
Q14. Magnesium blocks are attached to the steel hulls of ships to prevent corrosion. This method is called:
- A. tin plating
- B. electroplating
- C. sacrificial (cathodic) protection
- D. anodizing
Q15. When an acid is added to a yellow solution of K₂CrO₄, the solution turns orange because:
- A. Cr₂O₇²⁻ is converted into CrO₄²⁻
- B. a chromium(II) complex forms
- C. Cr⁶⁺ is reduced to Cr³⁺
- D. CrO₄²⁻ is converted into Cr₂O₇²⁻
Q16. In acidic medium, how many electrons does one MnO₄⁻ ion gain when it is reduced?
- A. 1
- B. 3
- C. 7
- D. 5
Q17. In acidic solution, how many moles of Fe²⁺ are oxidized by 1 mol of Cr₂O₇²⁻?
- A. 5
- B. 6
- C. 3
- D. 2
Q18. Urea is manufactured industrially by reacting:
- A. nitrogen with methane
- B. ammonia with nitric acid
- C. ammonia with carbon dioxide
- D. calcium cyanamide with water
Q19. The percentage of nitrogen in ammonium nitrate, NH₄NO₃, is:
- A. 46.7%
- B. 17.5%
- C. 35%
- D. 28%
Q20. Which fertilizer mainly supplies phosphorus to plants?
- A. Calcium superphosphate
- B. Potassium chloride
- C. Ammonium sulphate
- D. Urea
Q21. Gypsum is ground with cement clinker in order to:
- A. increase the lime content
- B. give cement its grey colour
- C. speed up the setting of cement
- D. slow down the setting of cement
Q22. Which compound in Portland cement is mainly responsible for its early strength after setting?
- A. Dicalcium silicate (2CaO·SiO₂)
- B. Calcium sulphate
- C. Tetracalcium aluminoferrite
- D. Tricalcium silicate (3CaO·SiO₂)
Q23. In the rotary kiln for cement, clinker is formed in the hottest (burning) zone at about:
- A. 400°C
- B. 3000°C
- C. 1500°C
- D. 800°C
Q24. In the Kraft (sulphate) process for paper pulp, wood chips are digested with a mixture of:
- A. NaOH and Na₂S
- B. Na₂CO₃ and NaCl
- C. H₂SO₄ and HCl
- D. Ca(OH)₂ and CaCO₃
Q25. In the Haber process, ammonia is made from N₂ and H₂ using:
- A. platinum catalyst at 900°C
- B. nickel catalyst at 25°C
- C. an iron catalyst at about 450°C and 200 atm
- D. V₂O₅ catalyst at 1 atm
Q26. In the petroleum industry, cracking is used to:
- A. join small molecules into larger ones
- B. separate crude oil into fractions by boiling point
- C. break large hydrocarbon molecules into smaller, more useful ones
- D. remove sulphur from crude oil
Q27. On the octane-number scale, the two reference fuels are given the values:
- A. isooctane = 0 and n-heptane = 100
- B. n-octane = 100 and n-heptane = 0
- C. isooctane = 100 and n-heptane = 0
- D. benzene = 100 and hexane = 0
Q28. Rain is described as acid rain when its pH is less than about:
- A. 5.6
- B. 7.0
- C. 6.5
- D. 3.0
Q29. Photochemical smog forms when sunlight acts on:
- A. sulphur dioxide and smoke particles only
- B. chlorofluorocarbons only
- C. carbon dioxide and water vapour
- D. nitrogen oxides and hydrocarbons
Q30. Assuming complete conversion, what mass of ammonia is obtained from 28 kg of nitrogen in N₂ + 3H₂ → 2NH₃?
- A. 17 kg
- B. 28 kg
- C. 34 kg
- D. 68 kg