Answer: spongy lead (Pb).
- A spongy lead (Pb)
- B lead dioxide (PbO<sub>2</sub>)
- C graphite rod
- D lead sulphate
Correct answer: A. spongy lead (Pb)
Explanation: In a lead storage battery the anode is spongy lead (Pb) and the cathode is PbO<sub>2</sub>; both convert to PbSO<sub>4</sub> during discharge.
In a Daniell cell, electrons flow externally from the zinc anode (oxidation) through the voltmeter to the copper cathode (reduction), while the salt bridge completes the circuit.
Concept context
Explore the link between chemical reactions and electricity. Covers galvanic cells, electrolysis, standard electrode potentials, the Nernst equation, and real-world applications like batteries and corrosion.