Crystal Structure | MCQs

Explanation

In NaCl, each sodium ion (Na⁺) is surrounded by six chloride ions (Cl⁻) in a cubic close-packed structure.

Therefore, the coordination number of Na in NaCl is 6.

Explanation

• Covalent network crystals, also known as giant covalent structures, are solids in which each atom is covalently bonded to its neighbors, forming a continuous network of chemical bonds.
• Examples include diamond, graphite, and silicon carbide.
• These materials have very high melting points due to the strong covalent bonds that hold them together.

Explanation

• Diamond is a crystalline solid that has a sharp melting point.
• Meaning it melts at a specific temperature (around 4000 K) with a minimal range.

Explanation

• Ionic crystals are typically characterized by high melting points due to the strong electrostatic forces between the positively and negatively charged ions.
• The attractive forces between oppositely charged ions are strong, requiring a significant amount of energy to overcome, resulting in high melting points.

Explanation

• In a NaCl crystal lattice, each sodium (Na+) ion is surrounded by six chlorine (Cl-) ions, forming an octahedral geometry.
• This means that each Na+ ion is coordinated by six Cl- ions, and vice versa.

Explanation

• At room temperature, most ionic compounds are crystalline solids, meaning they have a rigid and orderly crystal structure.
• This is because the strong electrostatic forces between the oppositely charged ions hold them in a fixed position, creating a three-dimensional lattice.

Explanation

Explanation

 Lead tetroxide (Pb₃O₄), also known as red lead, crystallizes in the monoclinic crystal system.

Explanation

 Cleavage is the tendency of a crystal to break along specific planes of weakness.

Copper, being a metal, has a unique atomic structure that doesn't exhibit distinct planes of weakness.

When stressed, it tends to deform rather than cleave, resulting in a jagged fracture. 

Explanation

 The crystal structures with a coordination number of 12 are Face-Centered Cubic (FCC) and Hexagonal Close-Packed (HCP).

In these structures, each atom is surrounded by 12 other atoms.