The question asks to identify the scientist credited with the discovery of the electron. This is a fundamental concept in atomic structure and requires knowledge of key historical figures in physics and chemistry.
D) J.J. Thomson is credited with the discovery of the electron in 1897 through his cathode ray experiments.
The question asks about the fundamental nature of the electric charge carried by an electron. This is a basic concept in physics and chemistry, relating to the structure of atoms and subatomic particles.
Correct Option: C) Negative
An electron is a fundamental subatomic particle that carries a single unit of negative electric charge. This is a universally accepted property in physics.
The question asks to identify the scientist credited with the discovery of the proton. This requires knowledge of the historical development of atomic theory and the contributions of key physicists to the understanding of subatomic particles.
Correct Option: D) Ernest Rutherford is credited with the discovery of the proton in 1919, following his work on the nuclear model of the atom and experiments involving the bombardment of nitrogen with alpha particles.
The question asks to identify the scientist credited with the discovery of the neutron. This requires knowledge of fundamental discoveries in atomic physics.
Correct Option: C) James Chadwick is credited with the discovery of the neutron in 1932. He bombarded beryllium with alpha particles and observed a highly penetrating, uncharged radiation, which he identified as the neutron.
The question asks about the direct discovery resulting from Rutherford's gold foil experiment. This experiment, also known as the Geiger-Marsden experiment, was crucial in understanding atomic structure.
Correct Option: D) Atomic nucleus. Rutherford's gold foil experiment provided the first experimental evidence for the existence of a small, dense, positively charged nucleus within an atom.
This question asks about the fundamental postulates of Bohr's atomic model. We need to recall the key features of how electrons are described in this model.
D) Fixed circular orbits of definite energy
This option accurately describes Bohr's second postulate. Electrons in Bohr's model are confined to specific, quantized circular orbits, and each orbit corresponds to a particular energy level. An electron does not radiate energy while in one of these orbits.