1. Who is credited with the discovery of the electron?
Answer:
Explanation:
J.J. Thomson discovered the electron through his cathode ray experiments.
2. The nucleus of an atom consists of:
Answer:
Explanation:
The nucleus of an atom contains protons and neutrons, while electrons orbit around the nucleus.
3. Which model proposed that electrons orbit the nucleus in fixed paths?
Answer:
Explanation:
Neils Bohr proposed that electrons move in fixed orbits or shells around the nucleus.
4. The spectral lines of hydrogen observed in the Lyman series lie in the:
Answer:
Explanation:
The Lyman series of the hydrogen spectrum lies in the ultraviolet region.
5. Alpha particles are essentially:
Answer:
Explanation:
Alpha particles are essentially helium nuclei, comprising 2 protons and 2 neutrons.
6. In Rutherford's alpha scattering experiment, most of the alpha particles:
Answer:
Explanation:
In the experiment, most alpha particles passed straight through, indicating that the atom is largely empty space.
7. The phenomenon where certain elements emit radiation spontaneously is called:
Answer:
Explanation:
Radioactivity is the spontaneous emission of radiation by unstable atomic nuclei.
8. Gamma rays are:
Answer:
Explanation:
Gamma rays are electromagnetic waves, specifically high-energy photons.
9. Who proposed the uncertainty principle?
Answer:
Explanation:
Werner Heisenberg proposed the uncertainty principle, which states that position and momentum of a particle cannot both be precisely determined simultaneously.
10. The atomic number of an element represents the number of:
Answer:
Explanation:
The atomic number of an element indicates the number of protons in its nucleus.
11. The Balmer series of hydrogen is observed in the:
Answer:
Explanation:
The Balmer series is a set of spectral lines of hydrogen observed in the visible region.
12. The atomic mass number represents the number of:
Answer:
Explanation:
The atomic mass number is the sum of the number of protons and neutrons in the nucleus.
13. The electron was first identified as a particle in:
Answer:
Explanation:
The electron was first identified as a distinct particle during the cathode ray experiments.
14. The charge on an electron is:
Answer:
Explanation:
Electrons carry a negative charge.
15. Which series of the hydrogen spectrum is observed in the infrared region?
Answer:
Explanation:
The Paschen series of the hydrogen spectrum is observed in the infrared region.