True/False Questions: Write T or F next to the questions, below: i. Metallic bon

Question

True/False Questions: Write T or F next to the questions, below: i. Metallic bonding is stronger than ionic bonding. ii. In SiO_2 covalent bonding prevalent; iii. Dislocation is a line defect while a susbtititional element in a matrix of crystalline material is a point defect. iv. Diffusion in a crystalline solid depends on many factors including vacancy concentration. v. The resolution in TEM is ~ 10.1 nm while in light optical microscope is ~0.5 mm; vi. There is no solid in which chemical bondng is 100% covelent bonding; vii. directions are perpendicular to each other in bcc crystal structure and not in fcc. viii. Packing density is the highest in both fee and hcp crystal structures.

Explanation / Answer

i) true

metallic bonds are real bonds that are found in elements whereas ionic bonds are the electrostatic attractions between oppositely charged ions.

ii) true

silicon has four valence electrons which it shares with 2 oxygen to form a covalent molecule.

iii) true

dislocation defects are linear defects as they are caused when the atoms dislocate from their positions in the crystal structure whereas substitutional element occupies a single position in crystal causing point defect.

iv) true

diffusion in crystals is directly proportional to vacancies present in it. The particles migrate into crystal by random jumping from one vacancy to another

v) false

Resolution is the shortest distance between two objects that can be observed by the obeserver using the instrument. resolution in TEM is about 0.2 nanometres and 200 nm for light optical microscope.

vi) true

No solid has 100 % covalent bonding. Every covalent bond has some ionic character and every ionic bond has some covalent character.

vii) false

The primitive lattice vectors are of equal length and orthogonal for simple cubic lattices but not for bcc and fcc.

viii) true

packing efficiency is the volume of spheres divided by total volume of the cell. So it is highest that is 74% for both fcc and hcp

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.