IELTS reading detail Practice

According to the passage, what is the main purpose of the membrane in a Reverse Osmosis system?

Question type: multiple choice · Difficulty: beginner

1. A. To heat the seawater to create steam
2. B. To add essential minerals to the water
3. C. To block salt molecules while allowing water molecules to pass
4. D. To mix the brine with ocean water

Explanation Preview

Paragraph C explains that the membrane 'contains microscopic pores that are large enough to let water molecules pass through but small enough to block the larger salt molecules'. This directly answers the question.

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