Please wait...
/
-
Which of these defects is known as dislocation defect?
The distance between an octahedral void and tetrahedral void in fcc lattice would be:
For fcc, the octahedral voids are located at centre of cube and the mid point of edges. The tetrahedral voids are located at 1/4 distance from the corners on each body diagonal. Considering the void at centre, surrounded by 8 tetrahedral voids, all at a distance of 3a/4 within the same unit cell. These have to be nearest voids, because any tetrahedral void in a neighbouring cell has to be at a larger distance(nearest point in a neighbouring cell is at a/2).
In fcc crystal lattice, edge length of the unit cell is 400pm. The diameter of the greatest sphere which can be fitted into the interstitial void without distortion of lattice is:
In fcc unit cell,
a2=4r
r=a2/4 =4002/4
=141.4pm
For octahedral void,
2(r+R)=a
2R=a-2r
=400-2*141.4=117.16 pm
So, the diameter of greatest sphere=117.16 pm
The radius of Ag+ ion is 126pm while that of I- ion is 216pm. The coordination number of Ag in AgI is:
r+/r- =126/216 =0.58
This corresponds to fcc structure, so The coordination number of Ag in AgI is 6.
A compound XY crystallizes in BCC lattice with unit cell edge-length of 480pm, if the radius of Y- is 225pm, then the radius of X+ is:
For BCC lattice, 2(r+ + r-)=3a
r+=(3*480)-225 =190.7 pm
CsCl crystallises in a body-centered lattice. If 'a' is its edge length then which of the following statements is correct?
Frenkel defect occur due to movement of smaller cations into interstitial space due to larger difference in ionic radii of cations and anions.
Frenkel defect is also known as dislocation defect.
Which of the following will show schottky defect?
Doping of silicon (Si) with Al leads to?
When semiconductors are doped by third group elements, there is deficiency of electrons and semiconductor is called p-type semiconductor.
Solids which have a random arrangement of atoms or ions are
Solids which do not have an ordered arrangement of their constituent ions but have a disordered arrangement are called amorphous solids. They lack long range order which is a characteristic of crystal.
Electrolytes show electrical conductivity in which state:
Electrolytes are substances that conduct electricity in the molten state or in an aqueous solution. By melting or dissolving in water, ions are free to move around. As a result, the solution can be made to conduct electricity.
Correct (-)
Wrong (-)
Skipped (-)