Which of the following statements are true: 1. LEDs fabricated from GaAs emit radiation in the ultraviolet region. 2. LEDs fabricated from GaAs emit radiation in the infra red region. 3. When a semiconductor is doped with pentavalent impurity, the resulting material is p-type. 4. A n-type semiconductor is electrically neutral.

Which of the following statements are true: 1. LEDs fabricated from Ga

1.	Which of the following statements are true: 1. LEDs fabricated from GaAs emit radiation in the ultraviolet region. 2. LEDs fabricated from GaAs emit radiation in the infra red region. 3. When a semiconductor is doped with pentavalent impurity, the resulting material is p-type. 4. A n-type semiconductor is electrically neutral.
A.	1 and 2 only
B.	3 and 4 only
C.	2 and 3 only
D.	1, 2, 3 and 4
Answer» B. 3 and 4 only

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