Tag: changes in physical state - boiling, evaporation and condensation

Questions Related to changes in physical state - boiling, evaporation and condensation

During hot sunny day, people sprinkle water on the roof because ______________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. they have more water to sprinkle

  2. water is cheapest thing available

  3. it has high latent heat of vapourisation

  4. None of the above

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Correct Option: C
Explanation:

People sprinkle water on the roof top during sunny days as water has high latent heat of vaporisation so it will absorb more heat and make the roof top cool.

On decreasing the surface area, the rate of evaporation _________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. increases

  2. decreases

  3. remains same

  4. Data insufficient

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Correct Option: B
Explanation:

On decreasing the surface area, fewer particles are exposed to the atmosphere. So the rate of evaporation decreases.

On decreasing the humidity, the rate of evaporation __________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. increases

  2. decreases

  3. remains same

  4. Data insufficient

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Correct Option: A
Explanation:

Rate of evaporation is inversely proportional to humidity as the water vapours are already present in humid condition.

Change of a liquid into vapors at any temperature below its boiling point is called as ______________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. solidification

  2. gasification

  3. evaporation

  4. liquifaction

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Correct Option: C
Explanation:

In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour. This phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.

Evaporation is a type of vaporization of a liquid that occurs from _________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. bottom of a solid

  2. bottom of a liquid

  3. surface of a gas

  4. surface of a liquid

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Correct Option: D
Explanation:

Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase that is not saturated with the evaporating substance. Evaporation occurs only at the surface of a liquid.

Water vapor is indirectly proportional to ___________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. temperature

  2. surface area

  3. humidity

  4. wind speed

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Correct Option: C
Explanation:

Humidity is the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases. Hence, it is indirectly proportional to humidity.

Why do clothes dry faster on a windy day?

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. Evaporation increases with increase in wind speed.

  2. Evaporation increases with increase in humidity.

  3. Evaporation decreases with increase in wind speed.

  4. The above statement is incorrect.

Show answer
Correct Option: A
Explanation:

Evaporation increases with increase in wind speed. With the increase in wind speed, the particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding. Hence, clothes dry faster on a windy day.

When liquid takes up heat from the surrounding, the surrounding ____________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. cools down

  2. heats up

  3. remains unchanges

  4. none of above

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Correct Option: A
Explanation:

Liquid requires latent heat of vaporization. So, when the liquid takes up the heat from the surrounding to vaporize, the temperature of surrounding reduces, and it cools down due to loss of heat.

Coolers are more effective in areas with ___________.

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. low humidity

  2. high humidity

  3. both a and b

  4. none of above

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Correct Option: A
Explanation:

Decrease in humidity increases the rate of evaporation. Coolers work on the concept of evaporation. In high humid areas, rate of evaporation is low and hence, cooler is ineffective. On the other hand, in low humid areas, the rate of evaporation is high which causes cooling and thus, coolers are effective in such areas.

Evaporation of water will be faster:

chemistry states of matter: boiling, evaporation and condensation atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. near the sea

  2. far away from the sea

  3. both at equal rates

  4. None of the above

Show answer
Correct Option: B
Explanation:

Increase in humidity, reduces the rate of evaporation. The area near sea will be more humid as compared to the area far away from the sea. Hence, evaporation will be faster far away from the sea.