Structure & Bonding MCQs PDF

1. Which best describes metallic bonding? a) Attraction between ions b) Shared pair of electrons c) Delocalised electrons and positive ions d) Covalent bonds between atoms Answer: c) Delocalised electrons and positive ions Explanation: Metallic bonding is characterised by a lattic...

1. Which best describes metallic bonding? a) Attraction between ions b) Shared pair of electrons c) Delocalised electrons and positive ions d) Covalent bonds between atoms Answer: c) Delocalised electrons and positive ions Explanation: Metallic bonding is characterised by a lattice of positive ions surrounded by a sea of delocalised electrons, which can move freely and contribute to conductivity. 2. What property of metallic bonds allows metals to conduct electricity? a) High melting points b) Delocalised electrons c) Strong nuclear forces d) Covalent bonding Answer: b) Delocalised electrons Explanation: The free-moving delocalised electrons in a metallic bond can carry an electrical charge through the metal. 3. Why are metals malleable? a) Presence of ionic bonds b) Delocalised electrons allow ions to slide past one another c) Weak intermolecular forces d) Rigid lattice structures Answer: b) Delocalised electrons allow ions to slide past one another Explanation: Delocalised electrons move with cations and maintain electrostatic attractions, allowing metals to be bent or shaped without breaking. 4. What is an ionic bond? a) Sharing of electrons between atoms b) Electrostatic attraction between oppositely charged ions c) Covalent bond with shared electron pairs d) Metallic bonding between delocalised electrons Answer: b) Electrostatic attraction between oppositely charged ions Explanation: An ionic bond involves the electrostatic attraction between cations and anions in a giant lattice structure. 5. Which substance typically forms an ionic bond? a) NaCl b) CO₂ c) H₂ d) CH₄ Answer: a) NaCl Explanation: NaCl (sodium chloride) forms an ionic bond as electrons are transferred from Na to Cl, creating oppositely charged ions. 6. Describe the conductivity of ionic compounds in solid and molten states. a) Conductive in both solid and molten states b) Non-conductive in both solid and molten states c) Conductive in solid state but not molten state d) Non-conductive in solid state but conductive when molten Answer: d) Non-conductive in solid state but conductive when molten  Explanation: Ionic compounds are non-conductive in solid state due to xed ions, but conduct electricity when molten as ions are free to move. 7. Which statement is true about simple covalent molecules? a) They have high boiling points b) They are always soluble in water c) They have strong intramolecular bonds but weak intermolecular forces d) They conduct electricity Answer: c) They have strong intramolecular bonds but weak intermolecular forces Explanation: Simple covalent molecules have strong covalent bonds within the molecule but weak forces between the molecules, leading to low boiling points. 8. Identify the type of intermolecular force typically found in non-polar covalent molecules. a) Hydrogen bonding b) Permanent dipole-dipole c) Ionic bonding d) Van der Waals forces Answer: d) Van der Waals forces Explanation: Non-polar covalent molecules generally interact through induced dipole (Van der Waals) forces. 9. Which substance is not a giant covalent structure? a) Diamond b) Graphite c) Water (H₂O) d) Silicon dioxide (SiO₂) Answer: c) Water (H₂O) Explanation: Water (H₂O) is a simple covalent molecule, whereas diamond, graphite, and silicon dioxide are giant covalent structures. 10. Why does diamond not conduct electricity? a) It has weak intermolecular forces b) It has no free electrons or ions c) It is made up of non-metal atoms d) It is a solid at room temperature Answer: b) It has no free electrons or ions Explanation: In diamond, all four valence electrons of each carbon atom are used in covalent bonds, leaving no free electrons to carry charge. 11. What causes the high melting point in ionic compounds? a) Delocalised electrons b) Strong covalent bonds c) Electrostatic attractions between ions d) Hydrogen bonding Answer: c) Electrostatic attractions between ions Explanation: The strong electrostatic attractions between the positively and negatively charged ions in an ionic lattice require a lot of energy to break. 12. What physical property is common in all metals? a) High solubility in water b) High electrical conductivity c) Presence of hydrogen bonds fi  d) Low melting points Answer: b) High electrical conductivity Explanation: Metals conduct electricity well due to the presence of delocalised electrons that can move freely throughout the structure. 13. Which of the following has a giant covalent structure with free-moving electrons? a) Diamond b) Graphite c) Iodine d) Ice Answer: b) Graphite Explanation: Graphite has layers of covalently bonded carbon atoms with delocalised electrons allowing it to conduct electricity. 14. What type of bonding leads to high malleability in metals? a) Covalent bonding b) Ionic bonding c) Metallic bonding d) Hydrogen bonding Answer: c) Metallic bonding Explanation: Metallic bonding allows the metal cations to slide past one another while maintaining the metallic bond's integrity, leading to high malleability. 15. Why do ionic compounds have high melting points? a) Van der Waals forces b) Hydrogen bonding c) Strong electrostatic forces between ions d) Weak covalent bonds Answer: c) Strong electrostatic forces between ions Explanation: The high melting points of ionic compounds result from the strong electrostatic attractions between the oppositely charged ions, requiring signi cant energy to break. 16. Which of these best explains why iodine is solid at room temperature? a) Strong covalent bonds within molecules b) Weak Van der Waals forces between molecules c) Strong Van der Waals forces between molecules d) Free-moving delocalised electrons Answer: c) Strong Van der Waals forces between molecules Explanation: Iodine molecules have many electrons that induce relatively strong dipole interactions collectively, causing its solid state at room temperature. 17. Which feature explains graphite’s ability to conduct electricity? a) Four covalent bonds per carbon atom b) Delocalised electrons between layers c) Strong covalent bonds within layers d) Van der Waals forces between layers Answer: b) Delocalised electrons between layers Explanation: Graphite has free-moving delocalised electrons between its layers, allowing it to conduct electricity. 18. What is the main cause of brittleness in giant covalent structures? a) Delocalised electrons b) Weak Van der Waals forces c) Directional nature of covalent bonds fi  d) Electrostatic attractions Answer: c) Directional nature of covalent bonds Explanation: In giant covalent structures, covalent bonds are directional and break if the structure is distorted, leading to brittleness. 19. Which structure does not conduct electricity in any state? a) Solid NaCl b) Molten MgCl₂ c) Diamond d) Graphite Answer: c) Diamond Explanation: Diamond does not conduct electricity because all electrons are used in covalent bonds, and there are no free electrons or ions. 20. What are the primary bonds in a molecule like CO₂? a) Ionic bonds b) Covalent bonds c) Metallic bonds d) Hydrogen bonds Answer: b) Covalent bonds Explanation: CO₂ is held together by covalent bonds, with each oxygen sharing two pairs of electrons with the central carbon atom. 21. Which best describes the structure of sodium chloride (NaCl)? a) Molecules with single covalent bonds b) A giant lattice of ions c) Layers of atoms with delocalised electrons d) Individual molecules with Van der Waals forces Answer: b) A giant lattice of ions Explanation: NaCl forms a giant lattice of alternating Na⁺ and Cl⁻ ions held together by strong electrostatic forces. 22. Why does silicon dioxide have a high melting point? a) Presence of free-moving ions b) Strong covalent bonds in its giant lattices c) Strong Van der Waals forces d) Delocalised electrons Answer: b) Strong covalent bonds in its giant lattices Explanation: Each silicon atom is covalently bonded to four oxygen atoms in a giant lattice structure, requiring lots of energy to break these bonds. 23. Which physical property is typical of metal elements? a) Low melting points b) Brittle c) Malleable and ductile d) Soluble in water Answer: c) Malleable and ductile Explanation: Metals are malleable and ductile because the layers of cations can slide past one another without breaking the metallic bond. 25. What is a likely property of a substance with ionic bonding? a) Conducts electricity when solid b) Low melting point c) Brittle and hard  d) Malleable Answer: c) Brittle and hard Explanation: Ionic compounds are typically hard and brittle due to strong ionic bonds in a rigid lattice structure which shatter when under force. 26. Which type of bonding explains the properties of ice? a) Ionic bonding b) Covalent bonding c) Hydrogen bonding d) Metallic bonding Answer: c) Hydrogen bonding Explanation: Ice has strong hydrogen bonding between molecules, forming hexagonal structures that result in expansion and lower density when frozen. 27. In metals, what allows for e cient transmission of heat and electrical conductivity? a) Strong Van der Waals forces b) Rigid covalent bonds c) Mobile delocalised electrons d) Ionic bonds Answer: c) Mobile delocalised electrons Explanation: Delocalised electrons in the metal structure can carry thermal and electrical energy quickly through the lattice. 28. Graphite and diamond are both allotropes of carbon. Their di erent properties arise due to a) Di erent atomic masses b) Di erent types of bonding c) Di erent arrangements of carbon atoms d) Di erent impurities present Answer: c) Di erent arrangements of carbon atoms Explanation: Diamond has each carbon bonded to four others in a tetrahedral structure, while graphite has layers of hexagonally arranged carbon atoms. 29. Which element forms giant covalent structures in the forms of both diamond and graphite? a) Silicon b) Carbon c) Sulfur d) Nitrogen Answer: b) Carbon Explanation: Carbon uniquely forms giant covalent structures as diamond and graphite, showcasing vastly di erent physical properties due to their structure. 30. A molecule with equal sharing of electrons between identical atoms is a) Polar b) Non-polar c) Ionic d) Metallic Answer: b) Non-polar Explanation: Molecules with identical atoms sharing electrons equally will have no dipole and are considered non-polar. ff ff ff ff ff ff ffi ff