ECAT — Engineering College Admission Test (UET)
Take the ECAT Chemistry — Chemical Bonding (Set 3): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer review. Covers 30…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. The shape of the SF₄ molecule is:
Answer: A. see-saw
Explanation: S has 4 bond pairs + 1 lone pair (sp³d); the lone pair sits equatorially, giving a see-saw shape.
Q2. XeF₄ has how many lone pairs on the central atom and what shape?
Answer: C. 2 lone pairs; square planar
Explanation: Xe has 8 valence electrons: 4 used in bonds, 4 left as 2 lone pairs; the pairs sit axially, giving a square-planar molecule (sp³d²).
Q3. The shape of the ClF₃ molecule is:
Answer: C. T-shaped
Explanation: Cl: 3 bond pairs + 2 lone pairs (sp³d); the lone pairs occupy equatorial positions, leaving a T-shape.
Q4. The ion ICl₂⁻ is linear. The reason is that the central iodine has:
Answer: C. three lone pairs in the equatorial plane of a trigonal bipyramid
Explanation: I has 7 + 1 = 8 electrons from outside: 2 bond pairs and 3 lone pairs (sp³d); lone pairs sit equatorially, leaving the two Cl atoms axial and 180° apart.
Q5. Which of the following has the smallest bond angle?
Answer: C. H₂S
Explanation: H₂S ≈ 92°, H₂O ≈ 104.5°, NH₃ ≈ 107°, CH₄ 109.5°; larger central atom with less electronegativity gives pure p bonding.
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Q6. The bond angle in NF₃ (about 102°) is smaller than in NH₃ (about 107°) because:
Q7. In the ion NH₄⁺ the nitrogen atom is hybridised as:
Q8. The hybridisation of the carbon atoms in graphite and the C–C–C bond angle in a layer are:
Q9. The number of σ and π bonds in acetonitrile, CH₃–C≡N, is respectively:
Q10. In the molecule CH₂=CH–C≡N, the hybridisations of the three carbon atoms from left to right are:
Q11. Using molecular orbital theory, the bond order of the O₂⁺ ion is:
Q12. Which of the following species is paramagnetic?
Q13. The order of bond lengths for the species O₂, O₂⁺ and O₂⁻ is:
Q14. The resonance hybrid of the carbonate ion (CO₃²⁻) has each C–O bond order equal to:
Q15. In the ozone molecule the two O–O bonds are equal in length because:
Q16. The formal charge on the central sulphur atom in the structure of SO₂ drawn as O=S=O with one lone pair on S is (S has 6 valence electrons):
Q17. Which of these molecules is non-polar despite having polar bonds?
Q18. Of the isomers of dichlorobenzene (C₆H₄Cl₂), the one with zero dipole moment is:
Q19. According to Fajans' rules, which compound has the greatest covalent character?
Q20. The lattice energy order for NaF, MgO and NaCl is expected to be:
Q21. Which of the following ionic solids has the highest melting point?
Q22. Percentage ionic character of a bond depends mainly on:
Q23. In the coordinate covalent bond formed when BF₃ reacts with NH₃, the electron pair is donated by:
Q24. The O–N–O bond angles in NO₂⁺, NO₂ and NO₂⁻ follow the order:
Q25. Metallic bonding is best described as:
Q26. Which of the following species has a bond order of 3?
Q27. Which of the following hydrogen halides has the highest boiling point owing to hydrogen bonding?
Q28. The molecule with the highest bond dissociation energy among the following is:
Q29. XeF₂ is a linear molecule. The number of lone pairs on the central xenon atom is:
Q30. SnCl₄ is a volatile liquid whereas SnCl₂ is a crystalline solid. This difference is best explained by: