Question

8. Which of the following properties DOES NOT describe metallic crystalline solids?
A. brittle B. ductile C. malleable D. good conductor of heat
9. Which of the following properties characterizes covalent network crystalline solids?
A. brittle
B. high melting point
C. poor conductor of electricity
D. with cations and anions very
10. Which of the following phrases about molecular crystalline solid is FALSE?
A. fairly soft B. poor thermal conduction C. made up of atoms or molecules D. very high electrical conduction
11. Which of the following phrases about ionic crystalline solid is TRUE?
A. very hard B. good thermal conduction C. high melting point D. very high electrical conduction
12. Why is metallic crystalline solid a good conductor of electricity?
A. Atoms are packed close together. B. Particles can move through the crystal. C. The charged particles move through the crystal. D. Strong attractive forces hold the atoms in the crystal.
13. Why is ionic crystalline solid characterized to be hard?
A. No charged particles move through the crystal.
B. Strong attractive forces hold the crystal together.
C. Mobile charged particles are present in the molten state.
D. Strong attractive forces have to be broken to melt the crystal.
14. Why is molecular crystalline solid characterized to have low melting point? A. No charged particles move through the crystal.
B. Weak attractive forces hold the crystal together.
C. No particles can move easily throughout the crystal
D. Weak attractive forces are broken when crystals melt.
15. Why is covalent network crystal characterized to be hard?
A. No charged particles move through the crystal.
B. Strong attractive forces hold the crystal together.
C. No particles can move easily throughout the crystal.
D. Strong attractive forces have to be broken in order to melt crystals.​

Answer 1

8. A - Brittle

Explanation:

• metallic crystalline are held together by metallic bonds , which are electromagnetic in nature.
• Thus they are ductile, malleable, and are good conductors of heat and electricity.

9. D - with cations and anions

Explanation:

covalent crystalline solids are hard, brittle, have high melting point,  and poor conductor of electricity.  Thus the answer is D.

10. D - Very high electrical conduction

Explanation:

molecular crystalline solids are insulators, have low melting point, and volatile.

11. A & C  

Explanation:

• Ionic crystals have strong interaction between the ions.
• They are hard, brittle and have high melting point.
• They do not conduct electricity in solid, but in molten and aqueous forms.

12. A - Atoms are packed close together

Explanation:

metallic crystals are electromagnetic in nature and they are good conductors of electricity.

13. B - particles can move through the crystals

Explanation:

ionic crystals are held in lattice due to electrostatic force of attraction in cation and anion as well as the repulsion with the like charges.

14. B - weak attractive forces hold the crystals together

Explanation:

• The force holding the ions are weaker than the covalent and ionic bond.

• Thus they have low melting and boiling point.

15.B - Strong attractive force hold the crystals

Explanation:

• Covalent bonds are extremely strong

• Rearranging or breaking the bonds require large amount of energy