Niels Bohr modified Rutherford's atomic model by proposing that:
A. The nucleus contains protons and neutrons.
B. Electrons are embedded in a positive sphere.
C. Electrons have wave-like properties.
D. Electrons revolve in fixed, discrete circular orbits called energy levels.
Answer: Option D
Solution (By JKExamLibrary)
Niels Bohr proposed his model in 1913 to overcome the defects of Rutherford's model. He stated that electrons revolve around the nucleus in specific, discrete circular orbits (shells) with fixed energy, and they do not radiate energy while in these orbits, explaining atomic stability.
Explanation:
Haber process synthesizes ammonia using iron catalyst. Solvay process for soda ash uses no solid catalyst but involves reactions with CO₂ and ammonia. Bayer's process for alumina uses NaOH, no catalyst. Hall-Héroult process is electrolytic for aluminium. Catalysis is key in many industrial processes: Contact (V₂O₅), Ostwald (Pt), hydrogenation (Ni).
Explanation:
Electronegativity is the tendency of an atom to attract shared electrons in a chemical bond. It increases across a period and decreases down a group. Fluorine, located at the top right of the periodic table (Group 17, Period 2), has the smallest atomic radius and highest effective nuclear charge, giving it the highest electronegativity (3.98 on Pauling scale).
Explanation:
Carbon's ability to form bonds with other carbon atoms (catenation) and its tetravalency (four valence electrons) allow it to form long chains, branches, and rings, leading to millions of organic compounds. The C-C bond is strong (bond energy ~348 kJ/mol). Silicon also shows catenation but to much lesser extent. Carbon also forms multiple bonds, enhancing diversity.
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