Hydrogen-oxygen fuel cell benefits and storage issues

Steps:

• Recall fuel cell reaction: 2H₂ + O₂ → 2H₂O + electricity, using hydrogen fuel and atmospheric oxygen.
• Identify advantage: Oxygen sourced from air, so only hydrogen needs onboard storage.
• Identify disadvantage: Hydrogen's low density requires compression to 700 bar, needing reinforced tanks for safety.
• Evaluate options against reaction and practical vehicle use.

Why A is correct:

• Matches fuel cell design: Cathode draws O₂ from air (per electrochemical definition), while H₂ storage demands high-strength tanks to contain pressurized gas without leaks.

Why the others are wrong:

• B: "Uses acid rain" is nonsensical; fuel cells produce water, not consume or generate acid rain.
• C: Oxygen is not sourced from water; water is the reaction product, not reactant.
• D: Oxygen not from water, and byproduct H₂O is neutral, not acidic to cause rain pollution.

Final answer: A