Na₂CO₃ is formed from NaOH (strong base) and H₂CO₃ (weak acid). Its aqueous solution is basic due to hydrolysis: CO₃²⁻ + H₂O ⇌ HCO₃⁻ + OH⁻. Strong acid + strong base salts are neutral (NaCl).
Explanation:
Teflon (PTFE) is polymerized tetrafluoroethene, repeating unit –CF₂–CF₂–. Option A is PVC, C is polythene, D is polystyrene. Teflon is highly inert, used in non-stick cookware.
Explanation:
Chlorofluorocarbons (CFCs), once widely used as refrigerants and propellants, are the primary culprits behind ozone depletion. When CFCs reach the stratosphere, UV radiation breaks them down, releasing chlorine atoms. A single chlorine atom can catalytically destroy thousands of ozone (O3) molecules.
Explanation:
Henry Moseley discovered that the atomic number (number of protons) is the fundamental property of an element, not atomic mass. He proposed the modern periodic law: properties are periodic functions of atomic numbers. Mendeleev's law was based on atomic mass, which had anomalies.
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