Wood has lower calorific value (~17 kJ/g) compared to coal (~25-35 kJ/g), methane (~55.5 kJ/g), and hydrogen (~142 kJ/g). It contains moisture and oxygen, reducing energy density.
Explanation:
Ernest Rutherford discovered the atomic nucleus through his gold foil experiment (1911). J.J. Thomson discovered the electron (1897). Chadwick discovered the neutron (1932). Bohr proposed the model of the atom with quantized energy levels (1913), not the electron. Rutherford also discovered the proton (1919). Naming discoveries correctly is important for competitive exams.
Explanation:
Pure water is a poor conductor of electricity. The presence of dissolved ionic impurities (salts) increases conductivity. Measuring specific conductance (or resistivity) is a quick method to check water purity; ultrapure water has conductivity ~0.055 µS/cm. Boiling point elevation also indicates impurities but is less sensitive for trace amounts. Conductivity meters are widely used in laboratories.
Explanation:
Cathode (negative electrode): 2H₂O + 2e⁻ → H₂ + 2OH⁻ (or 2H⁺ + 2e⁻ → H₂). Hydrogen gas is collected at the cathode. At the anode, oxygen is produced: 2H₂O → O₂ + 4H⁺ + 4e⁻. The volume of H₂ is double that of O₂.
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