1. 50 Multiple Choice Questions (MCQs)
Q1. The force of attraction between two atoms in a molecule is called:
a) Electrovalency
b) Chemical bond
c) Ionization energy
d) Electronegativity
Answer: b
Q2. The electrostatic force of attraction between oppositely charged ions is called:
a) Covalent bond
b) Electrovalent bond
c) Metallic bond
d) Coordinate bond
Answer: b
Q3. The number of electrons an atom loses or gains to form an ionic bond is known as:
a) Covalency
b) Electrovalency
c) Coordination number
d) Atomic number
Answer: b
Q4. Which of the following is an ionic compound?
a) CH4
b) NaCl
c) NH3
d) CCl4
Answer: b
Q5. In the formation of MgCl₂, the number of electrons lost by Mg atom is:
a) 1
b) 2
c) 3
d) 4
Answer: b
Q6. Which of the following has a covalent bond?
a) NaCl
b) MgO
c) Cl₂
d) CaO
Answer: c
Q7. The covalency of nitrogen in NH₃ is:
a) 1
b) 2
c) 3
d) 4
Answer: c
Q8. The type of bond in NH₄⁺ between nitrogen and the fourth hydrogen is:
a) Covalent
b) Ionic
c) Coordinate
d) Metallic
Answer: c
Q9. Which condition favors the formation of ionic compounds?
a) Low ionization potential of one atom
b) High electron affinity of another atom
c) Large electronegativity difference
d) All of the above
Answer: d
Q10. Which of the following is a polar covalent compound?
a) Cl₂
b) O₂
c) HCl
d) CH₄
Answer: c
Q11. Which compound has both ionic and covalent bonds?
a) H₂O
b) NH₄Cl
c) CH₄
d) NaCl
Answer: b
Q12. Which of the following will be non-polar?
a) H₂O
b) HCl
c) N₂
d) NH₃
Answer: c
Q13. Covalent compounds generally have:
a) High melting points
b) Low melting points
c) High density
d) Metallic luster
Answer: b
Q14. Ionic compounds conduct electricity in:
a) Solid state only
b) Molten or aqueous state
c) Gaseous state
d) Powder form
Answer: b
Q15. The bond formed by sharing of electron pairs provided by one atom only is:
a) Covalent
b) Coordinate
c) Metallic
d) Ionic
Answer: b
Q16. Which of the following is a coordinate compound?
a) NaCl
b) CH₄
c) K₄[Fe(CN)₆]
d) CaO
Answer: c
Q17. The electrovalency of Al is:
a) 1
b) 2
c) 3
d) 4
Answer: c
Q18. In the formation of NaCl, sodium undergoes:
a) Reduction
b) Oxidation
c) Hydrolysis
d) Neutralization
Answer: b
Q19. The EN difference in covalent bonds is:
a) Very high
b) Zero or negligible
c) Always equal to 2.0
d) Very low but not zero
Answer: b
Q20. Which is an example of a non-polar covalent compound?
a) H₂O
b) H₂
c) HCl
d) NH₃
Answer: b
Q21. Ionic compounds are generally:
a) Soft solids
b) Hard solids
c) Liquids
d) Gases
Answer: b
Q22. Which of the following contains all three bonds (ionic, covalent, coordinate)?
a) NaCl
b) (NH₄)₂SO₄
c) CH₄
d) MgO
Answer: b
Q23. Which is NOT a property of covalent compounds?
a) Low melting point
b) Volatile
c) Good conductor in solid state
d) Non-conductor of electricity
Answer: c
Q24. The NH₃ molecule is:
a) Non-polar
b) Polar
c) Ionic
d) Metallic
Answer: b
Q25. Which element has 2 electrons to lose?
a) Na
b) Ca
c) Al
d) N
Answer: b
Q26. A Lewis base has:
a) Deficiency of electrons
b) Lone pair of electrons
c) Positive charge
d) High EN
Answer: b
Q27. In CO₂, the type of bonding is:
a) Ionic
b) Polar covalent
c) Non-polar covalent
d) Metallic
Answer: c
Q28. Which of the following has the highest melting point?
a) CH₄
b) H₂O
c) NaCl
d) NH₃
Answer: c
Q29. The electron dot structure for MgCl₂ shows:
a) Transfer of 1 electron
b) Transfer of 2 electrons
c) Sharing of electrons
d) Metallic bonding
Answer: b
Q30. Which compound dissolves in water and conducts electricity?
a) CH₄
b) NaCl
c) CCl₄
d) H₂
Answer: b
Q31. Which one is a polar molecule?
a) CCl₄
b) CH₄
c) H₂O
d) BF₃
Answer: c
Q32. Which is a Lewis acid?
a) NH₃
b) H₂O
c) H⁺ ion
d) OH⁻ ion
Answer: c
Q33. What is the covalency of carbon in CH₄?
a) 1
b) 2
c) 3
d) 4
Answer: d
Q34. Ionic bond formation is a type of:
a) Oxidation reaction
b) Reduction reaction
c) Redox reaction
d) None of the above
Answer: c
Q35. Which of these is a good conductor in molten state?
a) H₂O
b) NaCl
c) CH₄
d) CCl₄
Answer: b
Q36. The EN difference in ionic bonds is:
a) Zero
b) Very low
c) High
d) Moderate
Answer: c
Q37. Which one is a non-polar molecule?
a) NH₃
b) CO₂
c) H₂O
d) HCl
Answer: b
Q38. Which bond is present in H₂?
a) Single covalent
b) Double covalent
c) Triple covalent
d) Ionic
Answer: a
Q39. Which of these contains coordinate bonds?
a) Zn(NH₃)₄₂
b) NaCl
c) CaO
d) CH₄
Answer: a
Q40. Which atom has valency 1?
a) Oxygen
b) Fluorine
c) Nitrogen
d) Carbon
Answer: b
Q41. In ionic compounds, the force of attraction is:
a) Weak
b) Strong
c) Negligible
d) Varies
Answer: b
Q42. The melting point of covalent compounds is generally:
a) High
b) Low
c) Same as ionic
d) Unpredictable
Answer: b
Q43. Which bond is strongest?
a) Ionic
b) Triple covalent
c) Double covalent
d) Single covalent
Answer: b
Q44. HCl is:
a) Non-polar
b) Polar
c) Ionic
d) Metallic
Answer: b
Q45. Which of the following will be soft solids?
a) Ionic compounds
b) Covalent compounds
c) Metals
d) All of the above
Answer: b
Q46. Electron affinity is highest for:
a) Metals
b) Non-metals
c) Metalloids
d) Noble gases
Answer: b
Q47. An example of coordinate compound is:
a) K₂SO₄
b) NaCl
c) K₄[Fe(CN)₆]
d) CO₂
Answer: c
Q48. Which type of compound is volatile?
a) Ionic
b) Covalent
c) Metallic
d) All of the above
Answer: b
Q49. Which process occurs in cation formation?
a) Reduction
b) Oxidation
c) Hydrolysis
d) Polymerization
Answer: b
Q50. Which type of bond is present in N₂?
a) Single covalent
b) Double covalent
c) Triple covalent
d) Ionic
Answer: c
10 Case-Based Questions (CBQs)
(Each CBQ has a small paragraph followed by sub-questions)
CBQ 1
A student added magnesium ribbon to chlorine gas and observed the formation of a white crystalline solid. This compound was hard, had a high melting point, and conducted electricity when molten.
- Name the compound formed.
- What type of bond is present in this compound?
- Which property confirms it is an ionic compound?
- Write the electron dot structure for the compound.
- Mention the oxidation and reduction processes in the reaction.
CBQ 2
Ammonia (NH₃) is prepared in the laboratory by heating ammonium chloride with slaked lime. NH₃ is a polar covalent compound, soluble in water, and can form a coordinate bond.
- Which atom in NH₃ provides a lone pair for coordinate bonding?
- Give one example of a compound where NH₃ forms a coordinate bond.
- Why is NH₃ polar?
- Draw the electron dot structure of NH₃.
- State one property of covalent compounds shown by NH₃.
CBQ 3
Sodium chloride crystals are dissolved in water, and the solution conducts electricity.
- Name the type of bonding in NaCl.
- Why can NaCl conduct electricity in aqueous state but not in solid state?
- What is the force of attraction between Na⁺ and Cl⁻ called?
- State one more property of ionic compounds.
- Draw the electron dot structure of NaCl.
CBQ 4
Carbon tetrachloride (CCl₄) is a colourless, non-polar covalent compound, insoluble in water but soluble in organic solvents.
- What type of bond is present in CCl₄?
- Why is CCl₄ non-polar even though it contains polar C–Cl bonds?
- Give one property of covalent compounds shown by CCl₄.
- Draw the electron dot structure of CCl₄.
- Is CCl₄ an ionic or covalent compound?
CBQ 5
In a lab experiment, a student mixed oxygen gas (O₂) and hydrogen gas (H₂) to form water (H₂O).
- What type of bond is present between the atoms in O₂?
- What type of bond is present between H and O in H₂O?
- Why is H₂O a polar molecule?
- Draw the electron dot structure of water.
- State one property of polar covalent compounds.
CBQ 6
Calcium oxide (CaO) is formed by heating calcium carbonate. CaO is hard, has a high melting point, and is soluble in water forming an alkaline solution.
- Which type of bonding is present in CaO?
- Write the electron dot structure of CaO.
- Why does CaO have a high melting point?
- Is CaO ionic or covalent?
- Write the reaction between CaO and water.
CBQ 7
In K₄[Fe(CN)₆], potassium ions are bonded ionically with the complex ion [Fe(CN)₆]⁴⁻, in which Fe is bonded to CN⁻ ions via coordinate bonds.
- How many types of bonds are present in this compound?
- Which atom provides electrons in the coordinate bond?
- Which ion acts as Lewis acid?
- Give one more example of a coordinate compound.
- Name the type of bond between K⁺ and [Fe(CN)₆]⁴⁻.
CBQ 8
Hydrogen chloride gas (HCl) is covalent in nature but conducts electricity in aqueous solution.
- Why does HCl conduct in aqueous solution?
- What type of bond is present in HCl gas?
- Draw the electron dot structure of HCl.
- Is HCl polar or non-polar?
- Give one property of covalent compounds shown by HCl gas.
CBQ 9
Nitrogen gas (N₂) is found to be inert under ordinary conditions and exists as a diatomic molecule.
- What type of bond is present in N₂?
- How many electron pairs are shared between the two nitrogen atoms?
- Draw the electron dot structure of N₂.
- Why is N₂ non-polar?
- Give one property of non-polar covalent compounds.
CBQ 10
Ammonium chloride (NH₄Cl) contains covalent, ionic, and coordinate bonds.
- Which atoms are bonded covalently in NH₄Cl?
- Between which atoms is the coordinate bond present?
- Which ions are bonded ionically in NH₄Cl?
- Draw the structure of NH₄⁺ ion.
- State one property of NH₄Cl that shows it contains ionic bonds.
10 Application-Based Questions
- Lithium forms an ionic bond with chlorine, but carbon forms a covalent bond with chlorine. Explain the reason in terms of ionization potential and electronegativity.
- In the manufacture of fertilizers, ammonia is stored in tanks made of steel. Explain why ammonia cannot be stored in copper containers.
- Sodium chloride is used for melting ice on roads during winter. Explain which property of ionic compounds makes it suitable for this purpose.
- Bottled oxygen for hospitals is stored at high pressure. Explain why oxygen exists as a covalent molecule despite being a gas.
- HCl gas is non-conducting, but its aqueous solution conducts electricity. Explain using bonding and ionization concepts.
- CCl₄ is used in dry cleaning but not for cleaning water-soluble stains. Explain in terms of solubility principles.
- Magnesium burns in oxygen producing a bright white light and forming magnesium oxide. Identify the type of bonding in MgO and explain why it has a high melting point.
- Hardness of water can be removed by using sodium carbonate (Na₂CO₃). Explain why Na₂CO₃ dissolves readily in water but CCl₄ does not.
- Nitrogen is used to fill potato chips packets. Explain why nitrogen is unreactive in terms of chemical bonding.
- Ammonium sulphate fertilizer contains nitrogen in covalent, ionic, and coordinate bonded forms. Explain how all three types of bonds are present in a single compound.
