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In the H₂–O₂ fuel cell used in the Apollo space programme, the electrolyte is:
AAqueous NaOH (concentrated)
BDilute H₂SO₄
CPure water
DAqueous HCl
Answer & Solution
Correct answer: A. Aqueous NaOH (concentrated)
Apollo H₂–O₂ fuel cell: H₂ and O₂ bubbled through **porous carbon electrodes (with Pt/Pd catalyst)** dipped in **concentrated aqueous NaOH** (alkaline fuel cell). Net reaction: 2H₂ + O₂ → 2H₂O. Efficiency ~70% vs ~40% for thermal plants.
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