. The most widely used semiconductors are
A: (i) and (ii)
B: (ii) and (iii)
C: (iii) and (iv)
D: (i), (ii), (iv),(iii)
Option A is correct.
Si(Silicon) and Ge(Germanium) are most widely used semiconductors because of their atomic structures.
They have 4electrons in valence shell which forms four covalent bonds with neighbouring atoms in crystal lattice which can be altered by adding dopants.
Whereas phosphorus and arsenic are dopants added to a pure semiconductor to increase their conductivity.
Therefore, option A is correct. ( (i) silicon (ii) germanium )