Evaporation

Q.

What is produced when potassium reacts with water? $2\mathrm{K}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to ?$

Q.

Why lime water turns milky when it gets exposed to carbon dioxide?

Q. What is a chemical change?

Q.

Cooking of rice is a chemical change.

Q.

Question 8 (c)

Fill up the blanks
Salt is obtained from seawater by the process of ___

Q. Give a reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away.

Q.

Why evaporation is a cooling process?

Q.

What are the factors affecting evaporation ?

Q.

During the evaporation of a liquid –

1. The temperature of the liquid will rise.

2. The temperature of the liquid will fall.

3. May rise or fall depending on the nature.

4. The temperature remains unaffected.

Q.

The temperature at which water vapourises into steam is called-

Q. What is latent heat of vaporization?

1. Heat absorbed when a substance changes phase from solid to gas.
2. Heat absorbed when a substance changes phase from liquid to gas.
3. Heat absorbed when a substance changes phase from gas to liquid.
4. Heat released when a substance changes phase from liquid to gas.

Q.

8. Explain why carbon dioxide is used in aerated drinks.

Q.

Why does snow melt slowly on mountain slopes?

Q.

The process of evaporation of water from the aerial parts of plants especially in leaves is called as __.

Q. Fill in the blanks:​
Camphor and ammonium chloride can ............​

Q. What do you observe when a glass of gas jar which appears empty is inverted over a gas jar containing Bromine vapours ? Name the phenomenon.

Q.

Why are able to sip hot tea or milk faster from a saucer rather than a cup?

Q.

Changes in which new substances are formed are called __ changes.

Q.

Conversion of Water Into Vapour by Heating Is Called?

1. Evaporation of Water

2. Burning of Fuels

3. Moving of a Wheel

4. Breaking of a Brick

Q.

93. How can we separate impurities present in water?

Q.

Explain the meaning of the statement. “ The specific latent heat of vaporization of alcohol is 204 kcal/kg.”

Q. Identify the factors affecting rate of evaporation of a liquid.

1. Humidity
2. Melting point
3. Temperature
4. Gravitation
5. Air pressure
6. Wind speed
7. Volume
8. Surface area

Q. Seawater does not freeze easily when compared to pure water. Why? [2 MARKS]

Q. Salt is obtained from sea water by drying it in the sun. This process is known as ______ .

1. filtration
2. evaporation
3. condensation
4. distillation

Q. The continuous circulation of water from Earth's surface to atmoshpere and again from atmosphere back to the Earth's surface is called ______.

1. oxygen cycle
2. nitrogen cycle
3. water cycle
4. carbon cycle

Q.

When cold water is kept in a glass, small droplets are formed on the surface of the glass after a while. How does this happen? What is this phenomenon called? Can the reverse of this phenomenon happen? If so, what is that process called? Explain with an example. [5 MARKS]

Q.

Which of the following options correctly differentiates evaporation and boiling?

1. Evaporation takes place at any temperature that is below the boiling point.

2. Evaporation takes place only above boiling temperature.

3. Evaporation and boiling are the same.

4. Evaporation takes place only at boiling temperature.

Q. What is the content of water in a water vapour ?

Q. Why do we prefer to sip hot tea with a saucer rather than a cup?

Q.

The process in which a liquid changes into its gaseous state at any temperature above its boiling point is called evaporation.

1. True
2. False