The correct answer is Electrons are embedded in a positively charged sphere. Explanation & Key Takeaways: • Thomson's Model of the Atom: In 1904, J.J. Thomson proposed a model of the atom often referred to as the "plum pudding model." According to this model, the atom is composed of a positively charged sphere with negatively charged electrons embedded in it, similar to raisins in a pudding. • Charge Neutrality: Thomson stated that the positive charge of the sphere is equal in magnitude to the total negative charge of the embedded electrons, making the atom electrically neutral. • Structure Description: The correct statement that aligns with Thomson’s model is that “Electrons are embedded in a positively charged sphere”. This was his attempt to explain the stability and neutrality of atoms. • Incorrect Statements: Other statements in the question, such as "The atom contains only neutrons and electrons" or "Electrons revolve around a central nucleus in fixed orbits," are incorrect as they describe later models of the atom, such as Rutherford's or Bohr's models. • Limitations: Thomson's model could not explain experimental results like the gold foil experiment by Rutherford, which later led to the discovery of the nucleus. Related Concepts: • J.J. Thomson: • He was a British physicist who discovered the electron in 1897 through his experiments with cathode rays. • Thomson was awarded the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases and his discovery of the electron. • Rutherford’s Model: • In 1911, Ernest Rutherford conducted the famous gold foil experiment, which showed that atoms have a dense, positively charged nucleus. • He proposed that electrons revolve around the nucleus in orbits, contradicting Thomson's model. • Bohr’s Model: • In 1913, Niels Bohr refined Rutherford's model by introducing the concept of fixed energy levels for electrons orbiting the nucleus. • This model explained the stability of atoms and the emission spectrum of hydrogen. • Modern Quantum Model: • The current understanding of atomic structure is based on quantum mechanics, where electrons are described as existing in probabilistic regions called orbitals. • This model incorporates principles such as the Heisenberg Uncertainty Principle and Schrodinger's wave equation. Important Notes: • Key Characteristics of Thomson’s Model: • Proposed the concept of a positively charged sphere with embedded electrons. • Explained the overall neutrality of atoms but failed to account for atomic structure complexity. • Did not address the arrangement of electrons or the presence of a nucleus. • Historical Context: Thomson’s model was significant as it was the first attempt to describe the internal structure of atoms, paving the way for more advanced theories. • Experimental Evidence: The gold foil experiment conducted by Rutherford invalidated Thomson's model by proving the existence of a nucleus.