Questions on Physical Properties of Ionic Compounds
20 Multiple-Choice Questions: Physical Properties of Ionic Compounds
Questions
1. Which of the following is a typical physical state of ionic compounds at room temperature?
A) Gas
B) Liquid
C) Solid
D) Plasma
E) Gel
2. Ionic compounds generally have:
A) Low melting points
B) High melting points
C) No melting point
D) Melting points below 0°C
E) Variable melting points unrelated to structure
3. Which property best explains the high melting points of ionic compounds?
A) Weak covalent bonding
B) Strong electrostatic attraction between ions
C) Van der Waals forces
D) Hydrogen bonding
E) Metallic bonding
4. Ionic compounds are generally:
A) Good conductors of electricity in solid state
B) Poor conductors of electricity in molten state
C) Good conductors of electricity when dissolved in water
D) Good conductors of electricity in all states
E) Poor conductors in all states
5. Why do ionic compounds conduct electricity when molten or dissolved in water?
A) Ions are free to move and carry charge
B) Electrons are free to move
C) Protons flow freely
D) Covalent bonds break
E) The crystal lattice remains intact
6. What is the typical color of most ionic compounds?
A) Colorless or white
B) Bright red
C) Green
D) Purple
E) Metallic gray
7. Ionic compounds tend to be:
A) Malleable and ductile
B) Brittle and hard
C) Soft and flexible
D) Elastic
E) Gaseous
8. Which property of ionic compounds causes them to shatter when struck?
A) Electron mobility
B) Ionic bonds flexibility
C) Alignment of like charges causing repulsion
D) Plastic deformation
E) Covalent bond breaking
9. The solubility of ionic compounds in water is generally:
A) Very low
B) Moderate to high
C) Zero
D) Dependent only on temperature
E) Dependent only on pressure
10. Which of the following ionic compounds is least likely to dissolve in water?
A) NaCl
B) KBr
C) BaSO₄
D) MgCl₂
E) LiF
11. Which is true about the density of ionic compounds compared to molecular compounds?
A) Generally higher density
B) Generally lower density
C) Same density
D) Density varies randomly
E) Density depends only on temperature
12. Ionic compounds are usually:
A) Good thermal insulators
B) Good thermal conductors
C) Poor thermal conductors
D) Good electrical insulators at all times
E) Gaseous at room temperature
13. What happens to the crystal lattice of an ionic compound when it melts?
A) It remains rigid
B) It breaks down, allowing ions to move freely
C) It becomes stronger
D) It forms covalent bonds
E) It becomes a gas instantly
14. Ionic compounds typically have:
A) Low vapor pressure
B) High vapor pressure
C) Vapor pressure equal to water
D) Variable vapor pressure
E) No vapor pressure
15. Why are ionic compounds generally solid at room temperature?
A) Low bond energy
B) High lattice energy holding ions in fixed positions
C) They have few atoms
D) Because they are gases at low pressure
E) Weak intermolecular forces
16. Which of the following ionic compounds has the highest melting point?
A) NaCl
B) KCl
C) MgO
D) CsCl
E) CaF₂
17. The hardness of ionic solids is mainly due to:
A) Metallic bonding
B) Strong ionic bonds in the crystal lattice
C) Hydrogen bonding
D) Weak Van der Waals forces
E) Flexibility of bonds
18. Ionic compounds usually have:
A) Low boiling points
B) High boiling points
C) Boiling points lower than their melting points
D) No boiling point
E) Same boiling point as covalent compounds
19. When an ionic compound dissolves in water, it is said to:
A) Disassociate into ions
B) Form covalent bonds with water
C) Remain as a solid
D) Become a gas
E) Become non-polar
20. Which of the following is NOT a typical physical property of ionic compounds?
A) High melting points
B) Conductivity in molten state
C) Brittleness
D) Malleability
E) Solubility in water
Answers with Explanations
1. C) Solid
→ Ionic compounds are generally solid at room temperature.
2. B) High melting points
→ Due to strong ionic bonds, a lot of energy is needed to break the lattice.
3. B) Strong electrostatic attraction between ions
→ Oppositely charged ions attract strongly.
4. C) Good conductors of electricity when dissolved in water
→ Ions move freely in solution to conduct electricity.
5. A) Ions are free to move and carry charge
→ In molten or aqueous states, ions are mobile.
6. A) Colorless or white
→ Many ionic compounds appear white or colorless, though some colored exceptions exist.
7. B) Brittle and hard
→ Strong bonds cause hardness; brittleness arises when ions shift and repel.
8. C) Alignment of like charges causing repulsion
→ Shifting layers cause like charges to align, leading to repulsion and fracture.
9. B) Moderate to high
→ Most ionic compounds dissolve well in polar solvents like water.
10. C) BaSO₄
→ Barium sulfate is poorly soluble in water.
11. A) Generally higher density
→ Ionic lattices pack ions closely, often resulting in higher density.
12. B) Good thermal conductors
→ Ionic solids can conduct heat better than many molecular solids.
13. B) It breaks down, allowing ions to move freely
→ Melting disrupts the lattice.
14. A) Low vapor pressure
→ Ionic compounds do not easily vaporize due to strong bonds.
15. B) High lattice energy holding ions in fixed positions
→ This keeps them solid under normal conditions.
16. C) MgO
→ Magnesium oxide has very high melting point due to strong charge and small ion size.
17. B) Strong ionic bonds in the crystal lattice
→ These bonds resist deformation, making solids hard.
18. B) High boiling points
→ Similar to melting points, strong bonds require high energy to vaporize.
19. A) Disassociate into ions
→ Dissolving separates the compound into free ions.
20. D) Malleability
→ Ionic solids are brittle, not malleable (which is typical of metals).
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