A binary solid has a primitive cubical structure with B- ions constituting the lattice points and A+ ions· occupying 25% of its tetrahedral holes. The molecular formula of the crystal is
A2B
AB3
AB2
A2B3
Which one of the following has a different crystal lattice from those of the rest?
Ag
V
Cu
Pt
B.
V
Vanadium (V) crystallises in bcc structures while Silver (Ag), Copper (Cu) and Platinum (Pt) crystallise in ccp structures.
The lattice energy of NaCl is 788 kJ mol-1. This means that 788 kJ of energy is required
to separate one mole of solid NaCl into one mole of Na (g) and one mole of Cl (g) to infinite distance
to separate one mole of solid NaCl into one mole of Na+ (g) and one mole of Cl- (g) to infinite distance
to convert one mole of solid NaCl into one mole of gaseous NaCl
to convert one mole of gaseous NaCl into one mole of solid NaCl
A solid compound contains X, Y and Z atoms in a cubic lattice with X atom occupying the comers. Y atoms in the body centred positions and Z atoms at the centres of faces of the unit cell. What is the empirical formula of the compound?
XYZ
X2Y2Z3
XYZ3
XY2Z3
KCl crystallises in the same type of lattice as does NaCl. Given that rNa+/ rCl-= 0.55 and rK+/rCl-= =0.74. Calculate the ratio of the side of the unit cell for KCl to that of NaCl.
1.123
0.0891
1.414
0.414
The cubic unit cell of Al (molar mass 27 g mol-1) has an edge length of 405 pm. Its denstiy is 2.7g cm-3. The cubic unit cell is
face centred
body centred
primitive
edge centred
Density of a crystal remains unchanged as a result of:
ionic defect
Schottky defect
Frenkel defect
crystal defect
High purity Si and Ge for semiconductor properties can be obtained by :
calcination
roasting
zone refining
thermic process