1. What is the charge of a single electron?
A. 1.6×10−19 C1.6 \times 10^{-19} \, \text{C}
B. −1.6×10−19 C-1.6 \times 10^{-19} \, \text{C}
C. 1.6 C1.6 \, \text{C}
D. −1.6 C-1.6 \, \text{C}
Answer: B
(The charge of an electron is −1.6×10−19 C-1.6 \times 10^{-19} \, \text{C}.)
2. Which subatomic particle determines the atomic number of an element?
A. Neutron
B. Electron
C. Proton
D. Nucleus
Answer: C
(The number of protons in the nucleus defines the atomic number of an element.)
3. What is the primary factor that determines whether a material is a conductor, semiconductor, or insulator?
A. Number of protons in the nucleus
B. Band gap energy
C. Density of the material
D. Atomic mass
Answer: B
(The band gap energy determines whether a material is a conductor, semiconductor, or insulator.)
4. What type of bond is primarily responsible for the electrical properties of metals?
A. Ionic bond
B. Covalent bond
C. Metallic bond
D. Hydrogen bond
Answer: C
(Metallic bonds allow free movement of electrons, which is why metals are good conductors of electricity.)
5. Which of the following materials is a good conductor of electricity?
A. Silicon
B. Copper
C. Glass
D. Rubber
Answer: B
(Copper is a good conductor due to its high electrical conductivity and free-moving electrons.)
6. In an atom, where are the electrons located?
A. Inside the nucleus
B. Orbiting around the nucleus
C. Between protons and neutrons
D. Alongside the nucleus
Answer: B
(Electrons orbit the nucleus in specific energy levels or shells.)
7. What is the primary electrical property of a semiconductor?
A. It has no free electrons.
B. It has a wide band gap.
C. It has a narrow band gap.
D. It cannot conduct electricity.
Answer: C
(Semiconductors have a narrow band gap, allowing controlled electrical conductivity.)
8. What happens to the electrical conductivity of metals as temperature increases?
A. It increases.
B. It decreases.
C. It remains constant.
D. It fluctuates randomly.
Answer: B
(As temperature increases, the resistance in metals increases, leading to a decrease in conductivity.)
9. Which type of material typically has the largest band gap?
A. Conductors
B. Insulators
C. Semiconductors
D. All have the same band gap
Answer: B
(Insulators have the largest band gap, making it difficult for electrons to move and conduct electricity.)
10. In a crystalline material, the arrangement of atoms is:
A. Random
B. Periodic and ordered
C. Amorphous
D. Fixed but irregular
Answer: B
(Crystalline materials have a periodic and ordered atomic arrangement.)