What can water vapour form by condensing on a cold surface?
Answer and explanation
Correct answer: Dew
The governing concept is condensation: when water vapour loses heat on or near a cold surface, it changes from a gas into tiny liquid water droplets. If these droplets collect on grass, leaves, windows, metal, or another exposed surface, the visible deposit is called dew. Hence option B is correct. A heat wave is a period of unusually hot weather, while dust and sand are solid particles and cannot be produced by the condensation of water vapour. The surface must become sufficiently cool, often near the dew point, for this process to occur. This example also shows that condensation is the reverse of evaporation: evaporation changes liquid water into vapour, whereas condensation changes vapour back into liquid droplets.
Frequently asked questions
What is the correct answer to this question?
Dew
Why is this the correct answer?
The governing concept is condensation: when water vapour loses heat on or near a cold surface, it changes from a gas into tiny liquid water droplets. If these droplets collect on grass, leaves, windows, metal, or another exposed surface, the visible deposit is called dew. Hence option B is correct. A heat wave is a period of unusually hot weather, while dust and sand are solid particles and cannot be produced by the condensation of water vapour. The surface must become sufficiently cool, often near the dew point, for this process to occur. This example also shows that condensation is the reverse of evaporation: evaporation changes liquid water into vapour, whereas condensation changes vapour back into liquid droplets.
Which subject and chapter does this question cover?
This is a Class 12 Geography question. Chapter: Water in the Atmosphere. Topic: Humidity, evaporation, and condensation.
