MCAT General Chemistry Question 179: Answer and Explanation
Home > MCAT Test > MCAT general chemistry practice tests
Test Information
- Use your browser's back button to return to your test results.
- Do more MCAT general chemistry practice tests.
Question: 179
14. Which of the following is the best explanation for the fact that a larger mass of electrodes are required for lead–acid batteries, as compared to other batteries, to produce a certain current?
- A. The lead–acid electrolyte, sulfuric acid, is diprotic and incompletely dissociates in solution.
- B. The energy density of lead–acid electrodes is higher than that of other batteries.
- C. The electrolytes in other batteries less readily dissociate than those of lead–acid batteries.
- D. The energy density of lead–acid electrodes is lower than that of other batteries.
Correct Answer: D
Explanation:
Compared to other cell types, lead-acid batteries have a characteristically low energy density, choice (D). While choice (A) is a true statement, the incomplete dissociation of sulfuric acid does not fully explain the low energy density of lead-acid batteries. Choice (C) is likely to be an opposite; the more easily the electrodes dissociate, the easier it is to carry out oxidation-reduction reactions with them.