Which of the following factors does not increase the rate of evaporation of water in a lake?

Analyze the question: We need the factor that does not increase the rate of evaporation of water in a lake.

Concept: Evaporation is the escape of the faster-moving molecules from a liquid surface. The rate depends on:

1. Temperature: higher temperature gives molecules more kinetic energy, so more escape.
2. Surface area: a larger exposed surface means more molecules can escape at once.
3. Wind (air movement): wind carries away vapour molecules above the surface, so fewer return to the liquid.
4. Humidity: drier air speeds up evaporation.
5. Pressure: higher atmospheric pressure makes it harder for molecules to leave the surface, since more air molecules push back on them. This reduces (or at best does not increase) evaporation.

Check each option:

• A. Increase in atmospheric pressure: this suppresses evaporation. It does not increase it. ✔ (the answer)
• B. Rise in temperature: increases evaporation. ✘
• C. Increase in surface area: increases evaporation. ✘
• D. Increase in wind speed: increases evaporation. ✘

**Answer: A.

Tip: Remember the "TAWD" factors that speed up evaporation: Temperature, Area, Wind, Dryness of air. Pressure is the odd one out, because higher pressure opposes evaporation (this is also why water boils at a higher temperature under higher pressure).