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 is called condensation.
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 colours
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 of tiny water droplets present in grass field evaporate slowly and continuously. The phenomenon of evaporation causes cooling effect.
Question 4.
Give examples of liquids other than water, which evaporate.
Answer:
Sanitizer(alcohol), acetone, petrol, ether, etc. are examples of liquids other than water, which evaporate.
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:
Blowing fan on wet clothes can fasten the drying process. When you blow air over wet clothes, the moving air helps to increase the rate of evaporation. This happens because the air moving across the wet surface helps to carry away the water vapour that is evaporating from the clothes, creating a drier environment around the clothing.
This air-flow helps to reduce the humidity and hence speeds up the rate of evaporation.
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 removed from drains is wet so it is kept in the forms of heaps next to the drain for 3-4 days. Meanwhile it gets dried due to evaporation and all extra water gets drained out. This moisture free sludge is safe as it is free from harmful microorganisms and then it is transported to a garden or a field where it can be used as manure.
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:
Evaporation is the process of conversion of liquid state of water to gaseous or vapour state at room or atmosphere temperature. We observe this phenomenon in our everyday life such as:
- Hot tea getting cold
- Wet cldihes drying under the sun
- Evaporation or perspiration from the body
- Drying of a mopped floor
- Drying of wet hair
By understanding the process of evaporation and the factors on which rate of evaporation depends we can increase its applications in our daily activities.
Thus we can fasten the process of evaporation by increasing the surface area, by increasing temperature, by decreasing humidity.
Question 8.
How is water present in the solid state in nature?
Answer:
Water is present in the solid state in nature in the form of hailstone, snow, ice caps, glaciers.
Question 9.
Reflect on the statement “Water is our responsibility before it is our right.” Share your thoughts.
Answer:
Enough water is available on the earth but the water available for use is very limited and is decreasing with over-usage. On the other hand, due to increase in human population, demand of water usable for drinking, preparation of food and also for industries, is increasing. Most of water in the oceans cannot be used directly as it is salty and unclean. Thus, it is our responsibility to save water and use it properly.
There is a strong need to conserve water, use it carefully and economically. Also avoid unnecessary wastage of water. Conservation programmes can be successful, if all people follow them faithfully.
Question 10.
The seat of a two-wheeler parked on a sunny day has become very hot. How can you cool it down?
Answer:
First of all move your two-wheeler into a shade under the tree, then you can keep a wet handerkerchief or cloth on th,e seat so that due to evaporation it gets cooled. Or you can pour cold water on the seat and let it gets evaporated or wipe it out.