Questions on Evaporation
20 Multiple-Choice Questions on Evaporation
1. What is evaporation?
A) A chemical reaction involving gases
B) A process where solids change directly to gas
C) The vaporization of a liquid at its surface below boiling point
D) Condensation of vapor into liquid
E) The boiling of water under pressure
2. Which condition increases the rate of evaporation?
A) High humidity
B) Low temperature
C) Less surface area
D) High wind speed
E) High atmospheric pressure
3. During evaporation, the molecules that escape from the surface:
A) Are the slowest molecules
B) Are at the same energy level as the average
C) Have lower kinetic energy
D) Have higher kinetic energy than the average
E) Have no kinetic energy
4. Evaporation is a:
A) Physical change
B) Chemical change
C) Nuclear change
D) Permanent transformation
E) Endothermic chemical reaction
5. Why does evaporation have a cooling effect?
A) It increases heat in the surrounding air
B) High energy particles remain behind
C) It releases energy into the surface
D) High energy particles leave the liquid, lowering average kinetic energy
E) It reflects radiation away from the surface
6. Which of the following will evaporate the fastest?
A) Water in a closed container
B) Water in a narrow beaker
C) Water with oil covering its surface
D) Water in a wide open dish
E) Water stored in a sealed glass bottle
7. Evaporation occurs at:
A) Only 100°C
B) Only at freezing point
C) Only in vacuum
D) All temperatures below the boiling point
E) Only at room temperature
8. What happens to the remaining liquid as evaporation continues?
A) It gains energy
B) Its temperature stays constant
C) Its temperature decreases
D) It becomes a gas
E) It solidifies
9. The rate of evaporation increases when:
A) The air is saturated
B) The liquid is covered
C) The temperature decreases
D) The surface area increases
E) The vapor pressure of air increases
10. Which of the following factors does not directly affect the rate of evaporation?
A) Temperature
B) Surface area
C) Humidity
D) Color of the container
E) Wind speed
11. Why does sweating cool the body?
A) The sweat reflects sunlight
B) The skin absorbs water
C) The body produces less heat
D) Evaporation of sweat absorbs body heat
E) Sweating increases oxygen in blood
12. Evaporation differs from boiling because:
A) Boiling occurs at the surface only
B) Evaporation requires high energy input
C) Boiling occurs throughout the liquid
D) Evaporation only occurs at boiling point
E) Boiling is a chemical change
13. Which of the following liquids will evaporate the slowest under the same conditions?
A) Alcohol
B) Acetone
C) Ether
D) Water
E) Petrol
14. In dry, hot climates, clothes dry faster because:
A) The air has more oxygen
B) Water boils at a higher temperature
C) The air is already saturated
D) Evaporation happens faster in dry and warm conditions
E) Water molecules move slower
15. When evaporation occurs in a closed container, it leads to:
A) Cooling of the environment
B) Continuous increase in evaporation
C) Condensation and dynamic equilibrium
D) No change in pressure
E) Precipitation
16. The energy required for evaporation is called:
A) Heat of fusion
B) Specific heat
C) Heat of vaporization
D) Heat of condensation
E) Activation energy
17. What best explains the smell of perfume spreading in a room?
A) Diffusion of solids
B) Sublimation of perfume
C) Chemical reaction with air
D) Evaporation and diffusion of volatile molecules
E) Decomposition of perfume
18. Evaporation is faster when the liquid has:
A) Low vapor pressure
B) High boiling point
C) Strong intermolecular forces
D) High vapor pressure
E) High density
19. Which change would slow down evaporation the most?
A) Using a fan
B) Placing liquid in direct sunlight
C) Reducing surface area
D) Increasing temperature
E) Lowering humidity
20. What happens to vapor pressure during evaporation in a closed container?
A) It remains zero
B) It decreases
C) It increases until equilibrium is reached
D) It fluctuates randomly
E) It instantly equals external pressure
- Questions on Atmospheric Pressure
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- Questions on Surface Tension
Answers with Explanations
1. C – Evaporation is the process where a liquid turns into vapor at its surface, below its boiling point.
2. D – High wind speed removes vapor molecules, increasing the evaporation rate.
3. D – Molecules with higher-than-average kinetic energy escape during evaporation.
4. A – Evaporation is a physical change because no new substances form.
5. D – High-energy molecules leave, lowering the average energy of remaining particles, cooling the surface.
6. D – Larger surface area allows more molecules to escape, increasing evaporation.
7. D – Evaporation can occur at all temperatures below boiling point.
8. C – The liquid cools down as energetic molecules escape.
9. D – Greater surface area leads to faster evaporation.
10. D – The color of the container doesn't significantly affect evaporation rate.
11. D – Sweat absorbs heat from the body as it evaporates.
12. C – Boiling involves vaporization throughout the liquid, unlike evaporation.
13. D – Water evaporates slower due to stronger hydrogen bonds.
14. D – Evaporation increases in dry, warm air due to low humidity and high temperature.
15. C – A dynamic equilibrium forms between evaporation and condensation in a closed container.
16. C – Heat of vaporization is the energy required to convert a liquid to vapor.
17. D – Perfume evaporates and its molecules diffuse through the air.
18. D – Liquids with high vapor pressure evaporate more easily.
19. C – A smaller surface area limits molecular escape, reducing evaporation.
20. C – In a closed container, vapor pressure increases until it balances condensation rate (equilibrium).
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