Observation

Most candidates performed well to question ‘a’ but a good number of them while attempting to explain the ‘b’ part, failed.

The expected answer is

(a) Doping is the introduction of impurity atoms into a semiconductor.

(b) Doping increases the number of charge carriers or electron holes thereby increases the conductivity of the semiconductors OR doping reduces the energy gap between the conduction band and the valence band that charges of minimum energy can therefore move into the conduction band.