In this note, we list some Chemical Bonding Chapter Questions and Answers of Applied Chemistry. These questions and answers are very important for final exam for polytechnic engineering or diploma engineering syllabus. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students as well.
Author Name: Arun Paul.
Chemical Bonding Chapter Questions and Answers for Polytechnic or Diploma Engineering Students of Applied Chemistry Syllabus of 1st Sem / 1st Year
Here, we have listed 25 important questions and answers from the chemical bonding chapter of the applied chemistry book for 1st-year/1st-semester polytechnic engineering or diploma engineering students.
1. What are the differences between an ionic solid and a covalent solid?
Answer:
| Property | Ionic Solid | Covalent Solid |
|---|---|---|
| Nature of Bond | Formed by electrostatic attraction between ions | Formed by sharing of electrons between atoms |
| Constituents | Cations and anions | Atoms or molecules |
| Melting & Boiling Point | Very high | High for network solids; low for molecular solids |
| Electrical Conductivity | Conducts in molten or aqueous state; not in solid | Does not conduct electricity |
| Solubility | Soluble in polar solvents (e.g., water) | Generally insoluble in water; soluble in non-polar solvents (for molecular solids) |
| Hardness | Hard but brittle | Very hard (network) or soft (molecular) |
| Examples | NaCl, KBr, CaCl₂ | Diamond, graphite, SiO₂, I₂ |
2. Why is it said that electrovalent (ionic) compounds have no real molecules?
Answer:
In ionic compounds:
- Ions are arranged in a continuous 3-dimensional crystal lattice.
- There are no separate, independent molecules like in covalent compounds.
- Each ion is surrounded by several oppositely charged ions.
- Therefore, we write a formula unit (e.g., NaCl), not a molecule.
Hence, ionic compounds do not exist as discrete molecules.
3. State the nature of bonds that exist in NH₄NO₃ (ammonium nitrate).
Answer:
Ammonium nitrate contains:
1. Covalent bonds
- Inside the ammonium ion (NH₄⁺) → N–H bonds are covalent.
- Inside the nitrate ion (NO₃⁻) → N–O bonds are covalent (with resonance).
2. Coordinate (dative) bond
- In NH₄⁺, one N–H bond is formed when nitrogen donates a lone pair to H⁺ → coordinate bond.
3. Ionic bond
- Between NH₄⁺ (cation) and NO₃⁻ (anion).
4. Why do crystals of ionic compounds not conduct electricity?
Answer: In the solid state ionic crystals do not conduct because the ions are fixed in the lattice and cannot move; conduction occurs when molten or in solution (ions become mobile).
5. Why has diamond a very high melting point?
Answer: Diamond is a 3-D network of strong covalent C–C bonds throughout the crystal; a large amount of energy is required to break this network.
6. Difference between the solid state structures of graphite and diamond — how is it reflected in electrical conductivity?
Answer:
- Diamond: each C is tetrahedrally bonded to 4 C atoms → 3-D covalent network, no free electrons → insulator.
- Graphite: layers of hexagonal carbon sheets with one delocalized π-electron per C → layers slide over each other and delocalized electrons move → good conductor (in plane).
7. Explain why metals are good conductors.
Answer: Metals have metallic bonding with a sea of delocalized (mobile) electrons that can move under an electric field and carry charge.
8. What is dry ice?
Answer: Solid carbon dioxide, CO₂(s) (sublimes on heating).
9. Indicate the nature of bond in the following compounds: K₂S, NaH, CO₂, NH₄Cl.
Answer:
- K₂S: ionic (electrovalent: K⁺ and S²⁻).
- NaH: ionic (Na⁺ and H⁻).
- CO₂: covalent (molecular, O=C=O).
- NH₄Cl: contains covalent bonds within NH₄⁺ and NO₃⁻ fragments, a coordinate (dative) bond in formation of NH₄⁺ (N donates lone pair to H⁺), and an ionic electrostatic attraction between NH₄⁺ and Cl⁻ (so all three types are present).
10. Which of the following molecules will have hydrogen bonds: CH₄, HCOOH, C₆H₆, pure HNO₃, HCl, CH₃COOH, HF, NH₃?
Answer: Hydrogen bonding will occur in HCOOH, pure HNO₃ (to some extent), HF, CH₃COOH, and NH₃. HCl may show very weak H-bonding; CH₄ and C₆H₆ do not.
11. Formula of dry ice is H₂O / CO₂ / H₂O₂.
Answer: CO₂
12. Bonds existing in NH₄Cl are —
(a) Covalent bond
(b) Electrovalent bond
(c) Both
Answer: (c) Both
Explanation:
- Inside NH₄⁺ → covalent + 1 coordinate bond.
- Between NH₄⁺ and Cl⁻ → ionic (electrovalent).
13. Name an allotrope of carbon that conducts electricity.
Answer: Graphite
14. Three types of bonds exist in KCl / NH₄Cl / NaCl.
Answer: NH₄Cl
(Because it has ionic, covalent, and coordinate bonds.)
15. The molecule/ion having one unpaired electron is —
(a) NO
(b) CO
(c) CN⁻
Answer: (a) NO
NO has an odd number of electrons → 1 unpaired electron.
16. Name a covalent solid.
Answer: Graphite, Diamond
17. Name a compound which contains both ionic and covalent bonds.
Answer: NH₄Cl
18. Ice is heavier than water — True or False?
Answer: False
Ice is less dense than water (that’s why it floats).
19. The atomic numbers of A and B are 12 & 17.
(i) Which is metal and which is non‐metal?
- A (Z = 12): 1s² 2s² 2p⁶ 3s² → Metal (Magnesium)
- B (Z = 17): 1s² 2s² 2p⁶ 3s² 3p⁵ → Non-metal (Chlorine)
(ii) Position of A and B in the periodic table.
- A: 3rd period, Group II
- B: 3rd period, Group VII
(iii) Formula of the compound between A and B.
Answer: AB₂ → MgCl₂
(iv) Nature of bond between A and B in the compound.
Answer: Ionic (Electrovalent) bond
20. Dry ice is an atomic solid — True or False?
Answer: False. Solid CO₂ is a molecular solid (discrete CO₂ molecules held by van der Waals forces).
21. Which bond has greater ionic character — HF or HCl?
Answer: HF. The electronegativity difference between H and F is larger, so HF is more polar (greater ionic character) than HCl.
22. Give one example each of an ionic solid, a covalent solid and a metallic solid.
Answer: Ionic solid: NaCl. Covalent solid: Graphite (or diamond). Metallic solid: Cu (copper).
23. High boiling point of water is due to —
(a) Ionic bond (b) H-bond (c) Covalent bond (d) Coordinate covalent bond
Answer: (b) H-bond. Strong hydrogen bonding between H₂O molecules raises boiling point.
24. Allotrope of carbon that can mark paper is —
(a) Diamond (b) Charcoal (c) Graphite (d) Coke
Answer: (c) Graphite. Graphite leaves marks because its layers slide and deposit carbon.
25. Why is solid CO₂ called ‘dry ice’?
Answer: Solid CO₂ looks like ice but sublimes directly to gas on warming, leaving the surface dry — hence “dry ice.”