If Z is the number of atoms in the unit cell that represents the closest packing sequence... A B C A B C..., the number of tetrahedral voids in the unit cell is equal to
Z
2Z
Z/2
Z/4
Assertion : Graphite is an example of tetragonal crystal system.
Reason : For a tetragonal system, a = b c, == 90°,= 120°
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If both assertion and reason are true but reason is not the correct explanation of the assertion.
If assertion is true, but reason is false.
Both assertion and reason are false statements.
An element (atomic mass 100 g/mol) having BCC structure has unit cell edge 400 pm. The density of element is (No. of atom in BCC (Z) = 2).
2.144 g/cm3
7.289 g/cm3
5.188 g/cm3
10.376 g/cm3
C.
5.188 g/cm3
Atomic mass of element = 100 g/mol
Cell edge= 400 pm= 400 x 10-12 = 4 x 10-10 and number of atoms in BCC (Z) = 2.
As the atomic mass ofthe metal is I 00 g/mol, therefore
mass of each atom (m) = = 16.6 x 10-23 g
The volume of unit cell = (4x 10-8) = 64 x 10-24 cm3.
And mass of unit cell = Z x m
= 2 x (16.6 x 10-23) = 33.2 x 10-23 g.
Therefore density of element =
= = 5.188 g/cm3.
The crystal system of a compound with unit cell dimensions a= 0.387 nm, b= 0.387 nm and c = 0.504 nm and 90° and 120° is
Cubic
Hexagonal
Orthorhombic
Rhombohedral
A solid AB has NaCl type structure. The radius of A+is 100 pm. What is the radius of B-?
190.47
540.13
525
78.12
Suppose the mass of a single Ag-atom is m. Ag metal crystallises in fcc lattice with unit cell of length a. The density of Ag metal in terms of a and 'm' is
Crystalline solids have
short range order
long range order
anisotropic distribution
All of these.