A Journey through States of Water Class 6 Question Answer Science Chapter 8

A Journey through States of Water Class 6 Questions and Answers NCERT Solutions

Class 6 Science Chapter 8 A Journey through States of Water Question Answer

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Question 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.
Answer:
(iv) The conversion of water vapour into its liquid state.

Question 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 colour
Answer:
(b) water colours

(ii) Writing on paper with
(a) pencil
(b) Ink pen
(c) ball point pen
Answer:
(b) ink pen

Question 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?
Answer:
Space around natural grass feels cooler because it absorbs heat from the sun and undergoes the process of transpiration and evaporation, which gives a cooling effect. Whereas, the plastic grass does not undergo such processes of evaporation and transpiration, so, it does not give a cooling effect.

Question 4.
Give examples of liquids other than water, which evaporate.
Answer:
Liquids other than water, which evaporate are alcohol, acetone, petrol, etc.

Question 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?
Answer:
Fans help in drying wet clothes as, they increase the air movement, and accelerates evaporation. Moving air carries away the water vapour that has formed above the wet clothes surface, reducing humidity and allowing more water to evaporate, thus causes rapid drying of wet clothes.

Question 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.
Answer:
The sludge is left in heaps for 3-4 days to allow the water content present in the sludge to evaporate. This reduces the weight and volume of the sludge, which makes it easier and cheaper to transport and also, it reduces the chances of spillage of the sludge, which contains harmful contaminants.

Question 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?
Answer:
Refer to the text in section 8.5 and 8.6 to understand the examples and process of evaporation in daily life.

Question 8.
How is water present in the solid state in nature?
Answer:
Water is present in the solid state in nature as
Ice It is found in ice caps, glaciers etc.
Snow It is found in mountains.
Hail It is a form of solid precipitation that falls as balls of ice.
Frost A thin layer of ice that forms on a cold surface, when the temperature is less than 1°C.

Question 9.
Reflect on the statement “Water is our responsibility before it is our right.” Share your thoughts.
Answer:
Even though we all have the right to use water, we must also take responsibility for it. This means we need to be careful not to waste water and to keep our water sources clean. If we waste water or pollute it, we might not have enough clean water for ourselves and others in the future. So, it is our job to use water wisely and to help protect it.

Question 10.
The seat of a two-wheeler parked on a sunny day has become very hot. How can you cool it down?
Answer:
The hot seats of a two-wheeler parked on a sunny day can be cooled down by

1. Placing a damp cloth or towel over the seat. The water in the cloth will help absorb some of the heat.
2. Lightly spraying the seat with water using a spray bottle. This can help cool it down faster.
3. Using a seat cover to protect the seat from getting too hot.
4. Put the two-wheeler in a shaded spot, like under a tree.

NCERT Solutions for Class 6 Science Chapter 8 A Journey through States of Water

Intext Questions

Question 1.
Hand sanitiser disappears as you rub it on your hands. What happens to it? (Page 145)
Answer:
Hand sanitiser disappears as you rub it on your hands because hand sanitisers contains alcohol, which evaporates faster. When we rub it between our hands, it thus disappears and gives cooler sensation.

Question 2.
What do you think is the reason for the disappearance of water from the puddles? Is it due to (i) seeping of water into the ground or (ii) evaporation of water or (iii) both of these? (Page 145)
Answer:
The water in the puddle disappears due to both the reasons, i.e., seepingof water into the ground and evaporation of water.

Question 3.
What differences do you see in evaporation on a cold day versus a hot day? (Page 153)
Answer:
On a hot day, when the temperature is higher, the rate of evaporation increases as, when water is heated, it escapes more easily into the air as vapour. Whereas, on a cold day, rate of evaporation decreases as the temperature is lower.

Question 4.
Do clothes dry faster or slower on a windy day? (Page 155)
Answer:
Clothęs dry faster on a windy day as, increased air movement or wind accelerates evaporation. Moving air carries away the water vapour that has formed above the liquid surface, reducing humidity and allowing more water to evaporate.

Question 5
If you want to dry your clothes on a rainy day, how can you make it faster? (Page 156)
Answer:
You can dry your clothes faster on a rainy day by either hanging clothes near a fan or heater or by using a hair dryer to dry it.

Let’s Investigate

Activity 1 (Page 144)

Aim : To observe the melting of ice into water.
Materials Required Ice cube, cup, etc.

Procedure :

1. Take an ice cube and put it in a cup.
2. Leave the cup on the table.

Observation : After leaving an ice cube at table, we observe that ice gets converted into water.

Conclusion : We can conclude that the solid ice is converted into liquid water by the process of melting.

Viva Questions :

1. Can you convert the water back into solid ice?
2. What is melting?

Activity 2 (Page 144-145)

Aim : To observe the evaporation of water.
Materials Required Steel plate, tablespoon, water, etc.

Procedure :

1. Take a steel plate.
2. Add a tablespoon of water on it.

Observation : After leaving steel plate for sometime, we observe that water gets disappeared completely.

Conclusion : We can conclude that the liquid water gets converted into gaseous state by the process called evaporation.

Viva Questions :

1. Why does water in utensils gets disappeared if left for sometime, after washing?
2. What is evaporation?

Activity 3 (Page 146)

Aim : To observe the condensation of water vapour.
Materials Required Glass tumbler, cold water, ice cubes, etc.

Procedure :

1. Take cold water in a glass tumbler.
2. Add a few ice cubes into it.
3. Leave it undisturbed for five minutes.

Observation : After leaving this glass tumbler undisturbed for sometime, we observe that some tiny droplets of water appear on the outer surface of the glass tumbler.

Conclusion : We can conclude that when the water vapour present in the air comes in contact with a cold surface, it forms tiny water droplets. This process of conversion of water vapour into liquid water, is known as condensation.

Viva Questions :

1. Why do we see dew drops on plants in the morning?
2. What is condensation?

Activity 4 (Page 153)

Aim : To observe the effect of surface area on rate of evaporation.
Materials Required Water, small cap of a bottle, plate, etc.

Procedure :

1. Take water in a small cap of a bottle.
2. Take the same amount of water in a plate.
3. Keep both of them on the table, near each other.
4. Record the time taker. for the water to completely evaporate in each case.

Observation : We observet that water in the plate evaporates faster than the water present in the small cap of a bottle.

Conclusion : We can conclude that when the water is spread out more, like on a plate, the area exposed to air is larger, thus, evaporation is faster. Less surface area, like a small cap of a bottle, limits the area available for evaporation and thus slows down the process.

Viva Questions :

1. Why do water disappears faster in large puddles than small puddles?
2. Name one factor that influences the rate of evaporation.

Activity 5 (Page 155)

Aim : To observe the effect of temperature on rate of evaporation.
Materials Required Water, 2 caps of bottles, etc.

Procedure :

1. Take two identical caps of bottles.
2. Fill them with equal amounts of water.
3. Keep one of them in direct sunlight and the other one in shade.
4. Record the time taken for the water to completely evaporate in each case.

Observation : We observe that water in the cap kept in direct sunlight evaporates faster than the water present in the cap of a bottle kept in shade.

Conclusion : We can conclude that when the temperature is higher, i.e. under the sunlight, the rate of evaporation increases as, when water is heated, it escapes more easily into the air as vapour.

Viva Questions :

1. Why do water disappears faster on a hot sunny day than on a winter evening?
2. Does temperature influence the change of states of water?

Activity 6 (Page 158)

Aim : To understand the role of dust particles in the formation of clouds.
Materials Required Water, empty plastic bottle, newspaper, cup, etc.

Procedure :

1. Take an empty one litre plastic bottle.
2. Pour one cup of water into it.
3. Close the lid of the bottle tightly. Squeeze the bottle quickly and release the bottle. Do this continuously for 2-3 times.
4. Add a small burnt piece of newspaper into the water.

Observation : We observe that some haziness or cloudiness appears above the water in the bottle.

Conclusion : We can conclude that this haziness is due to the presence of burnt newspaper, which provides very small dust particles, and water vapour condenses around it to form clouds.

Viva Questions :

1. What is the role of dust particles in the water cycle?
2. What is a water cycle?

Do it Yourself (DIY)

1. Aim To explore how the candle wax transforms from a solid to a liquid when heated, and then back to a solid as it cools.
2. Aim To observe the cooling effect of evaporation by dipping one of your hands in water and letting it dry in air.

Curiosity Class 6 Science Book Solutions