Solutions to NCERT Class 6 Science Curiosity Chapter 8 A Journey Through States of Water

Welcome students! The solutions to all Chapter 8 ‘Let us Enhance your learning’ questions are included in this material. We have also included solutions to many extra questions of various formats on this topic as well for you to practise. You will see similar questions in your exams, so we suggest you study them in detail for maximum benefit.

Solutions to ‘Let us enhance our learning’ (Page No 161) of NCERT Class 6 Science Curiosity Chapter 8 A Journey Through States of Water

1. Which of the following best describes condensation?

(i) The conversion of water into its vapour state.
(ii) The process of water changing from a liquid into gaseous state.
(iii) The formation of clouds from tiny water droplets.
(iv) The conversion of water vapour into its liquid state

Solution:

(iv) The conversion of water vapour into its liquid state

2. Identify in which of the given processes, evaporation is very important—

(i) Colouring with

(a) crayons                (b) water colours

(c) acrylic colours     (d) pencil colours

(ii) Writing on paper with

(a) pencil                    (b) ink pen                (c) ball point pen

Solution:

Evaporation is very important in the following processes:

(i) Colouring with (b) water colours.

Explanation: In case of water colours, the water needs to evaporate for the painting to get dried.

(ii) Writing on paper with (b) ink pen.

Explanation: Ink pens contain liquid ink which needs to evaporate for the writing to get dried, otherwise the writing will get smudged.

3. We see green coloured plastic grass at many places these days. Space around natural grass feels cooler than space around the plastic grass. Can you find out why?

Solution:

Space around natural grass feels cooler than space around the plastic grass because evaporation of water contained inside the natural grass which happens from the surface. This results in cooling of the space around the natural grass.

4. Give examples of liquids other than water, which evaporate.

Solution:

Examples of liquids other than water which evaporate are alcohol, acetone and perfume.

5. Fans move air around, creating a cooling sensation. It might seem strange to use a fan to dry wet clothes since fans usually make things cooler, not warmer. Normally, when water evaporates, it requires heat, not cold air. What do you think about this?

Solution:

Fans blow away the air saturated with water vapour from the vicinity of the clothes. The drier air which replaces it has the capacity to absorb more water vapour from the clothes. Thus, the rate of evaporation increases and clothes dry faster.

6. Usually, when sludge is removed from drains, it is left in heaps next to the drain for 3–4 days. Afterward, it is transported to a garden or a field where it can be used as manure. This approach reduces transportation cost of the sludge and enhances the safety of individuals handling it. Reflect upon it and explain how.

Solution:

When sludge is left in heaps next to the drain for 3–4 days, the water from the sludge evaporates, thereby reducing the weight of the sludge. This allows more sludge to be transported and reduces the overall transportation cost. The absence of water due to evaporation also makes it impossible for harmful microorganisms to survive in the sludge, thereby enhancing the safety of individuals handling it.

7. Observe the activities in your house for a day. Identify the activities that involve evaporation. How does understanding the process of evaporation help us in our daily activities?

Solution:

The activities that involve evaporation are:

(i) Drying Clothes:When you hang clothes on a clothesline they lose water through evaporation.

(ii) Boiling Water: When water is boiled on the stove, it evaporates and changes state to form steam.

(iii) Sweating: During sweating, water evaporates from our bodies, cooling us down.

(iv) Cooking: During cooking on the stove, water evaporates to form steam.

(v) Sitting Under a Fan: When we sit under a fan after sweating, the sweat evaporates from our bodies, which cools us down.

Understanding the process of evaporation helps us in our daily activities in the following ways:

Efficient Drying: If we understand how evaporation works, we can easily find the right conditions for efficient drying of clothes. For examples we can choose a sunny and windy area to hang our clothes.

Body Temperature Regulation: Understanding how evaporation works can help us cool down during the intense heat during the summer. For example, we can sit under a fan during hot weather to cool down.

Cooking: Understanding how evaporation of water happens during cooking helps in adjusting recipes and knowing the correct cooking times.

Cooling of Drinking Water: We can understand how to cool down drinking water by understanding the process of evaporation.

8. How is water present in the solid state in nature?

Solution:

Water is present in the solid state in nature in the following forms:

(i) Ice: Ice is found on top of mountains, glaciers, in the polar regions as icebergs etc. It is also found in lakes, rivers and oceans during winter when the water freezes.

(ii) Snow: Found inplaces of extreme cold during winter. Formed when water vapour in the atmosphere condenses into ice crystals in extreme cold and fall to the ground as snowflakes.

(iii) Hail: Ice pellets that fall the ground instead of rain during thunderstorms.

(iv) Frost: Thin layer of icewhich forms on surfaces during extreme cold weather.

9. Reflect on the statement “Water is our responsibility before it is our right.” Share your thoughts.

Solution:

Only a small portion of water available on the Earth is fit for use by plants, animals and humans. Therefore, it our responsibility to avoid wasting water, keep it free from pollution and to use it judiciously. We should also raise awareness regarding the importance of water conservation.

10. The seat of a two-wheeler parked on a sunny day has become very hot. How can you cool it down?

Solution:

You can cool down the set of the two-wheeler on a sunny day by sprinkling water on it. The water will evaporate due to the sun’s heat, which will cool the seat down. The two-wheeler can also be parked in a shady area for some time to avoid exposure to excess heat.

Solutions to In Text Questions of NCERT Class 6 Science Curiosity Chapter 8 A Journey Through States of Water

1. (Page 144) I think the water has been absorbed by the soil on the playground. What do you think about it?
Solution:
Some water has been absorbed by the soil on the playground and some of it has evaporated.

Extra Questions to Complement Solutions to NCERT Class 6 Science Curiosity Chapter 8 A Journey Through States of Water

Very Short Answer Type:

1. What are the three states of water?
Answer:
Ice, water and water vapour.

2. Why does water left on the surface of utensils dry up after some time?
Answer:
Water left on the surface of utensils dries up after some time due to evaporation and forms water vapour.

3. Give examples of evaporation of water taking place at room temperature.
Answer:
Drying of wet clothes, mopped floor, and sweat on our body.

4. Why are there water droplets on the outer surface of a glass tumbler filled with water?
Answer:
When the water vapour present in the air comes in contact the cold surface of the glass tumbler, it condenses to form water droplets.

5. Name the two states of water which do not have a fixed shape.
Answer:
Water and water vapour.

6. How can you change water from a liquid to a solid state?
Answer:
By cooling it, typically by placing it in a freezer.

7. Why does dew form on plants in the morning?
Answer:
When water vapour in the air comes in contact with the cool surfaces of plants in the morning, condensation occurs and vapour changes to liquid state. This is known as dew.

8. Suppose you place a bowl of water on a hot sunny day on a balance. What will happen to the reading on the balance as the day progresses?
Answer:
The reading of the balance will decrease because of evaporation of water from the bowl due to high temperature.

Short Answer Type:

1. Suppose you take an uncovered glass tumbler with cold water and weigh it using a digital weighing balance. What do you observe and why?
Answer:
You will observe that the reading of the digital weighing balance slowly increases. This is because the water vapour from the air comes in contact with the cold surface of the glass tumbler and gets converted into water droplets on the glass tumbler by condensation. This results in an increase in weight of the glass tumbler as a whole.

2. Why is water sprinkled on the floor or the roof during summer?
Answer:
The water sprinkled on the floor or the roof evaporates due to the high temperature in the summer. This imparts a cooling effect to the floor or the roof. This helps to cool down during the intense heat.

3. How are clouds formed?
Answer:
When air moves higher above the Earth’s surface, it becomes cooler and cooler. At certain heights, the air gets so cool that the water vapour in it condenses into water droplets which are generally formed around dust particles. These small droplets float in the air and form what we know as clouds.

4. Briefly describe what you mean by water cycle.
Answer:
The water from the ocean and the Earth’s surface evaporates into the atmosphere as vapour, which rises and forms clouds. The droplets in the clouds get bigger and fall to the Earth as rain, hail or snow. These melt and ultimately the water flows back to the oceans. This circulation of water is known as the water cycle.

5. Our planet is mostly made up of oceans. Then why is there scarcity of drinking water?
Answer:
Only a small portion of water available on the Earth is fit for use by plants, animals and humans. Most of the water is in the oceans is too saline and cannot be used directly. We only drink water from rivers, lakes and groundwater. With increasing population, the demand for water for drinking and other activities is also increasing. Due to these reasons, there is scarcity of drinking water.

6. Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help? If yes, how?
Answer:
Yes, spreading it near an anghiti or heater would help because the heat will increase the rate of evaporation of water from your school uniform quickly. Therefore, your school uniform will dry quickly.

7. To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.
Answer:
When people breathe, it releases water vapour. When the water vapour comes into contact with the relatively colder surface of the glasses, it condenses to make them wet.

8. What happens if there is no water cycle?
Answer:
The following things would happen in the absence of the water cycle:

(i) Our sources of water for drinking and other purposes would be contaminated.

(ii) If there is no water cycle, the level of water in ponds and wells as well as groundwater will not be replenished and will become scarce. This leads to drought.

Long Answer Type:

1. What are the conditions that favour evaporation of water?

Answer:

The conditions which favour evaporation of water are:

(i) Surface Area: If the surface area of the vessel is larger, the rate of evaporation is also higher because the area exposed to air is larger.

(ii) Temperature: Higher temperature favours the rate of evaporation.

(iii) Humidity: Low humidity favours evaporation. If the amount of water in the air is already high (more humidity), water evaporates slowly.

(iv) Wind Speed: Higher wind speed favours evaporation. The wind carries away the air saturated with water vapour from the vicinity of the water. The air that replaces it has the capacity to absorb more water vapour. Hence, rate of evaporation is faster.

2. Why is water precious?

Answer:

Here is why water is precious:

(i) Water is essential for living beings.

(ii) Living beings cannot survive without water and water is essential for producing many things.

(iii) Crops like wheat, rice, pulses, vegetables and many other foods require water to grow.

(iv) Some of the fibre that we use for making fabric comes from plants which require water to sustain themselves.

(v) Most of the water that is present on our planet is contained in oceans which contain saline water and that is not suitable for drinking and domestic, agricultural and industrial needs.

(vi) Therefore, to preserve water we need to conserve our water sources like lakes, ponds, rivers as well as groundwater because they are scarce.

Fill in the Blanks:

evaporation, lighter, cooling, humid, liquid

(a) In the water cycle, water from oceans, rivers, and lakes is converted into water vapour through __________.

(b) The state of water that flows is __________.

(c) _________ is necessary for the condensation of water vapour into liquid water.

(d) Water vapour is _________ than air, hence is rises upwards.

(e) The amount of water vapour in the air is more on rainy days and hence rainy days are more _________.

Answers:

(a) In the water cycle, water from oceans, rivers, and lakes is converted into water vapour through evaporation.

(b) The state of water that flows is liquid.

(c) Cooling is necessary for the condensation of water vapour into liquid water.

(d) Water vapour is lighter than air, hence is rises upwards.

(e) The amount of water vapour in the air is more on rainy days and hence rainy days are more humid.

Match and Pair:

Column A	Column B
(i) Gaseous state of water	(a) Condensation
(ii) Process of water vapour turning into liquid water	(b) More humid
(iii) Summers	(c) Fresh water
(iv) Winters	(d) Water vapour
(v) Drinking water	(e) Less humid

Answer:

Column A	Column B
(i) Gaseous state of water	(d) Water vapour
(ii) Process of water vapour turning into liquid water	(a) Condensation
(iii) Summers	(b) More humid
(iv) Winters	(e) Less humid
(v) Drinking water	(c) Fresh water

            
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