Which statement about evaporation is true?

Which statement about evaporation is true?

• A. Evaporation heats water to sterilize it completely.
• B. Evaporation removes all dissolved minerals and pollutants from water.
• C. Evaporation requires chemical additives to purify water.
• D. Salt and most mineral or chemical pollutants do NOT evaporate with water.

Answer: (D)

Evaporation is the process by which liquid water turns into water vapor at the surface. What makes the statement true is that most dissolved salts and minerals are non-volatile; they do not vaporize with water. When water evaporates, it leaves behind these dissolved substances, which is why seawater concentrates salt as it boils. The vapor that rises is largely pure water, though some very volatile impurities can co-evaporate, they’re not the norm for common minerals and chemicals. That’s also why distillation uses evaporation plus condensation to separate nearly pure water from dissolved substances. So the key idea is that salts and many pollutants do not evaporate with water, which is why evaporation alone doesn’t remove them.

Evaporation is the process by which liquid water turns into water vapor at the surface. What makes the statement true is that most dissolved salts and minerals are non-volatile; they do not vaporize with water. When water evaporates, it leaves behind these dissolved substances, which is why seawater concentrates salt as it boils. The vapor that rises is largely pure water, though some very volatile impurities can co-evaporate, they’re not the norm for common minerals and chemicals. That’s also why distillation uses evaporation plus condensation to separate nearly pure water from dissolved substances. So the key idea is that salts and many pollutants do not evaporate with water, which is why evaporation alone doesn’t remove them.