Which of the following methods is most commonly used to purify water in a laboratory setting?

• A. Distillation without filtration
• B. Heating water without removing impurities
• C. Filtration followed by evaporation
• D. Adding salt and stirring

Answer: (C)

Verified step by step guidance

1. Understand the goal: purifying water means removing impurities and contaminants to obtain clean water.
2. Review each method: Distillation involves boiling water and condensing the steam, which removes many impurities but is often combined with filtration for better purity.
3. Heating water alone does not remove impurities; it only raises the temperature and may kill some microbes but leaves dissolved substances behind.
4. Adding salt and stirring actually adds impurities rather than removing them, so this method does not purify water.
5. Filtration followed by evaporation is effective because filtration removes solid particles and some impurities, and evaporation can remove dissolved substances by turning water into vapor, which then condenses as purified water.