Shapes of Molecules Practice Questions PDF

1. What determines the shape of a simple molecule? * (A) The number of atoms in the molecule * (B) The number of electron pairs around the central atom * (C) The electronegativity of the atoms * (D) The size of the atoms 2. What is meant by a "lone pair" of electrons? * (A) A pair of electrons shar...

1. What determines the shape of a simple molecule? * (A) The number of atoms in the molecule * (B) The number of electron pairs around the central atom * (C) The electronegativity of the atoms * (D) The size of the atoms 2. What is meant by a "lone pair" of electrons? * (A) A pair of electrons shared between two atoms * (B) A pair of electrons not involved in bonding, belonging to one atom * (C) A single electron involved in bonding * (D) A pair of electrons transferred from one atom to another 3. Do lone pairs or bonding pairs of electrons repel more? * (A) Bonding pairs * (B) Lone pairs * (C) They repel equally * (D) Neither repel 4. What is the shape of a molecule with 2 bonding pairs and 0 lone pairs around the central atom? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Bent 5. What is the shape of a molecule with 3 bonding pairs and 0 lone pairs around the central atom? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Trigonal pyramidal 6. What is the shape of a molecule with 4 bonding pairs and 0 lone pairs around the central atom? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Square planar 7. What is the shape of a molecule with 2 bonding pairs and 2 lone pairs around the central atom? * (A) Linear * (B) Bent * (C) Tetrahedral * (D) Trigonal planar 8. What is the shape of a molecule with 3 bonding pairs and 1 lone pair around the central atom? * (A) Tetrahedral * (B) Trigonal planar * (C) Trigonal pyramidal * (D) Bent 9. What is the approximate bond angle in a linear molecule? * (A) 90° * (B) 109.5° * (C) 120° * (D) 180° 10. What is the approximate bond angle in a trigonal planar molecule? * (A) 90° * (B) 109.5° * (C) 120° * (D) 180° 11. What is the approximate bond angle in a tetrahedral molecule? * (A) 90° * (B) 109.5° * (C) 120° * (D) 180° 12. What is the approximate H-O-H bond angle in a water molecule? * (A) 104.5° * (B) 107° * (C) 109.5° * (D) 180° 13. What is the approximate H-N-H bond angle in an ammonia molecule? * (A) 104.5° * (B) 107° * (C) 109.5° * (D) 120° 14. What is the shape of a CO₂ molecule? * (A) Linear *(B) Bent *(C) Tetrahedral *(D) Trigonal Pyramidal 15. What is the shape of a BF₃ molecule? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Trigonal pyramidal 16. What is the shape of a CH₄ molecule? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Trigonal pyramidal 17. What is the shape of a NH₃ molecule? * (A) Linear * (B) Trigonal planar * (C) Tetrahedral * (D) Trigonal pyramidal 18. What is the shape of a H₂O molecule? * (A) Linear * (B) Bent *(C) Tetrahedral *(D) Trigonal pyramidal 19. Lone pairs of electrons reduce the bond angle by approximately how many degrees *per lone pair*? * (A) 1° * (B) 2.5° * (C) 5° * (D) 10°  20. Which of the following best explains why lone pairs reduce bond angles? * (A) Lone pairs are smaller than bonding pairs. * (B) Lone pairs are closer to the nucleus and repel more strongly. * (C) Bonding pairs are closer to the nucleus and repel more strongly. * (D) Lone pairs are further from the nucleus. Answers and Explanations 1. Answer: (B) The number of electron pairs around the central atom Explanation: Electron pairs (both bonding and lone pairs) repel each other, determining the shape. 2. Answer: (B) A pair of electrons not involved in bonding, belonging to one atom Explanation: This is the de nition of a lone pair. 3. Answer: (B) Lone pairs Explanation: Lone pairs are held closer to the central atom's nucleus and exert a greater repulsive force. 4. Answer: (A) Linear Explanation: Two electron pairs arrange themselves as far apart as possible (180°). 5. Answer: (B) Trigonal planar Explanation: Three electron pairs arrange themselves 120° apart in a at triangle. 6. Answer: (C) Tetrahedral Explanation: Four electron pairs arrange themselves in a tetrahedron (109.5° angles). 7. Answer: (B) Bent Explanation: The two lone pairs repel the bonding pairs, reducing the bond angle from 109.5° to approximately 104.5°. 8. Answer: (C) Trigonal pyramidal Explanation: The lone pair repels the three bonding pairs, creating a fl fi pyramid shape with a bond angle of about 107°. 9. Answer: (D) 180° Explanation: This is the angle that maximizes the distance between two electron pairs. 10. Answer: (C) 120° Explanation: This is the angle that maximizes the distance between three electron pairs in a plane. 11. Answer: (B) 109.5° Explanation: This is the characteristic bond angle in a tetrahedral arrangement. 12. Answer: (A) 104.5° Explanation: The two lone pairs on the oxygen atom reduce the bond angle from the ideal tetrahedral angle. 13. Answer: (B) 107° Explanation: The one lone pair on the nitrogen atom reduces the bond angle from the ideal tetrahedral angle. 14. Answer (A) Linear Explanation: 2 double bonds, no lone pairs. 15. Answer: (B) Trigonal planar Explanation: Three bonding pairs, no lone pairs. 16. Answer (C) Tetrahedral Explanation: 4 bonding pairs, 0 lone pairs. 17. Answer (D) Trigonal pyramidal Explanation: 3 bonding pairs and 1 lone pair. 18. Answer (B) Bent Explanation: 2 bonding pairs and 2 lone pairs. 19. Answer: (B) 2.5° Explanation: This is the approximate reduction in bond angle per lone pair, according to the documents. 20. Answer: (B) Lone pairs are closer to the nucleus and repel more strongly. Explanation: This is the key reason why lone pairs have a greater repulsive effect than bonding pairs. Powered by pmfm.ai Request Support