Sodium has body centred packing. If the distance between two nearest atoms is 3.7 Å, then the lattice parameter is
3.3 Å
3.9 Å
4.3 Å
4.8 Å
Phosphorus
Aluminium
Magnesium
Both (b) and (c)
Diamond is very hard because
it is covalent solid
it has large cohesive energy
high melting point
insoluble in all solvants
Which of the following when added as an impurity into silicon produces n-type semiconductor?
P
Al
B
Mg
Which one of the following is the weakest kind of the bonding in solids?
Ionic
Metallic
Van der Waals'
Covalent
In a junction diode, the holes are due to
protons
extra electrons
neutrons
missing electrons
At absolute zero, Si acts as
non-metal
metal
insulator
None of these
When n-type semiconductor is heated
number of electrons increases while that of holes decreases
number of electrons and holes remain same
number of electrons and holes increases equally
n-type semiconductor
p-type semiconductor
n-type conductor
emitter
base
collector
Any of the above depending upon the nature of transistor.
