Tag: atmospheric pressure and boiling point

Questions Related to atmospheric pressure and boiling point

Drinking of hot tea from a saucer preferred to a cup, 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. Surface area

  2. Material of the saucer

  3. Thermal conductivity

  4. Colour

Show answer
Correct Option: A
Explanation:

The surface area of milk poured in a saucer is more than that in the cup. The more the surface area, the more is the rate of evaporation which causes cooling. Therefore, the tea present in saucer becomes cool faster than in a cup.


Hence, option A is correct.

Which of the following statements is/are wrong?

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. At room temperature, evaporation of water is rapid as compared to ethanol

  2. Water is more viscous as compared to ethanol

  3. Liquid drops are spherical in shape

  4. Clothes are easily dried on dry days as compared to humid days

Show answer
Correct Option: A,B
Explanation:

Clothes are easily dried on dry days as compared to humid days because evaporation is inversely proportional to humidity.

Ethanol evaporates faster because the intermolecular forces are strong in water due to hydrogen bonding.
Water is more viscous compared to ethanol due to its cohesivity adhesivity.

Rinku and Pinku had half day schools during summer. They used to go to school by auto. Observed that the auto driver covered the top of the auto by some mats which keeps the auto cool. Which of the following phenomenon is involved here?

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. Condenzation

  2. Evaporation

  3. Sublimation

  4. Diffusion

Show answer
Correct Option: B
Explanation:

Evaporation is the phenomena involved as it makes the surroundings cooler by removing heat inside the auto. The auto driver keeps the mats which is made of a material which helps in evaporation like cotton.

Which among the following statements is true?

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. The rate of evaporation in a coastal area is less because of high humidity

  2. The rate of evaporation in a coastal area is more because of presence of water bodies

  3. The rate of evaporation is independent of humidity

  4. The rate of evaporation is directly proportional to humidity

Show answer
Correct Option: A
Explanation:

The rate of evaporation in a coastal area is less because of high humidity because high humidity represents the higher concentration of water vapour in the air due to which temperature of surrounding atmosphere decreases and rate of evaporation also decreases.


Hence, the correct option is $\text{A}$

Identify the substance that evaporates at room temperature.

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. Water

  2. Oil

  3. Kerosene

  4. Ammonium chloride

Show answer
Correct Option: C
Explanation:

Kerosene evaporates at room temperature (liquid to gas) as it is volatile and have a low vapour pressure.


Water and oil need heat for evaporation (liquid to gas). 

Hence, option C is correct.

Which one of the following statements related to the process of evaporation is incorrect?

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 occurs at any temperature.

  2. Evaporation takes place within the liquid not on the surface.

  3. Temperature may change during evaporation.

  4. No bubbles are formed in the liquid during evaporation.

Show answer
Correct Option: B
Explanation:

Evaporation is a type of vaporization which occurs on the surface of the liquid. The evaporation process can occur at a temperature below the boiling point. So by evaporation, only the liquid molecules on the surface get converted to the water vapour.


Hence, the correct option is $\text{B}$

The rate of evaporation decreases with an increase in _________.

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. humidity

  2. temperature

  3. wind speed

  4. surface area

Show answer
Correct Option: A
Explanation:

Evaporation is a type of vaporization of liquid that occurs from the surface of liquid, to gaseous phase that is not saturated with the evaporating substance. If the air is saturated with great amount of water causing high humidity, it decreases the rate of evaporation of water.

The rate of evaporation does not depends on:

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. surface area

  2. wind speed

  3. humidity

  4. type of particles

Show answer
Correct Option: D
Explanation:

The rate of evaporation does not depend on the type of particles because it completely depends upon the surface area of the liquid, if surface area is large evaporation will be maximum. Evaporation also depends upon wind speed, if the wind is flowing at a higher speed, then the rate of evaporation increases. Same will be applied in the case of humidity. Humidity decreases evaporation.

Which of the following is a surface phenomenon?

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. Boiling

  2. Evaporation

  3. Dilution

  4. None of the above

Show answer
Correct Option: B
Explanation:
$Boiling$ is a bulk phenomenon because all molecules get energy on heating.

$Evaporation$ is a surface phenomenon as the molecules of the surface gets sufficient energy to overcome the force of attraction which will help in converting to the vapor phase.

$Dilution$ is also a bulk phenomenon as the volume of solution increases in the whole solution.

So, the correct answer is (B).

How does the perspiration leave cooling effect on our body?

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. Sweat particles absorb energy from the surrounding to change into vapour thereby reducing the temperature

  2. The particles release energy into the atmosphere and the temperature decreases

  3. The particles absorb energy from the body and converts into vapour thereby increasing the temperature

  4. None of the above

Show answer
Correct Option: A
Explanation:

When the ambient temperature is above body temperature, then radiation, conduction, and convection all transfer heat into the body rather than out. Since there must be a net outward heat transfer, the only mechanisms left under those conditions are the evaporation of perspiration from the skin and the evaporative cooling from exhaled moisture.