Answer: hydrogen gas.
- A chlorine gas
- B hydrogen gas
- C sodium metal
- D oxygen gas
Correct answer: B. hydrogen gas
Explanation: In brine electrolysis, water is reduced at the cathode to give H<sub>2</sub> (Na<sup>+</sup> is not discharged from aqueous solution); Cl<sub>2</sub> forms at the anode.
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.