(2)Which of the following elements are most likely to serve as donor impurities

(2)Which of the following elements are most likely to serve as donor impurities in germanium? (a) Bromine (b) Gallium (c) Silicon (d) Phosphorus (e) Magnesium.(3)When a pnp junction transistor is used as an amplifier a small signal in the __________ current results in a large signal in the __________ current.(a) Collector; base (b) Base; collector (c) Emitter; base (d) Emitter; collector (e) Collector; base(4)When light strikes the p-type semiconductor in a pn junction solar cell(a) Only free electrons are created.(b) Only positive holes are created.(c) Both electrons and holes are created.(d) Positive protons are created.(e) None of these is correct.