Chapter 8 A Journey through States of Water Class 6 Science Curiosity NCERT Solutions
Chapter 8 A Journey through States of Water NCERT Solutions Class 6 Science
Question 1. Why does air containing water vapour go up in the atmosphere (thin layer of air
that surrounds the Earth)?
Answer
As we know, gas balloons containing lighter gases go up in the air. Similarly, water vapour is lighter than air, causing it to rise.
Let us enhance our learning
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.
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
Answer
(i) (b) Evaporation is very important in colouring with water colours.
(ii) (b) Evaporation is very important in writing on paper with ink pen.
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
Natural grass produces a cooling effect through the processes of transpiration and evaporation. Natural grass absorbs moisture from air and this water then evaporates by absorbing heat from the surroundings. The temperature of surrounding decreases when the water evaporates which creates a cooling effect.
On the other hand, plastic grass doesn't exhibit these properties.
4. Give examples of liquids other than water, which evaporate.
Answer
Some of the examples of liquid which evaporate:
- Alcohol
- Oil
- Petrol
- Acetone
- Sanitizer
- Milk
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
The rate of evaporation increases when air is moving. When we turn on the fan, the air moving across the wet clothes carry away the water vapour from them creating a drier environment around the cloth. This air-flow helps to reduce the humidity and hence speeds up the rate of evaporation. This help in drying the cloth under the fan.
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 removed from the drain is wet and leaving them next to the drain for 3-4 days helps water evaporate from it. This process makes the sludge lighter and easier to transport. As a result, transportation costs are reduced.
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
Some daily activities that involve evaporation:
- Drying clothes
- Cooling milk
- Mopping the floor
- Sweating
- Cooking
Knowing that water evaporates faster in sunlight and with increased air movement, and that the rate of evaporation decreases with higher humidity, helps us in our daily activities.
8. How is water present in the solid state in nature?
Answer
Water exists in the solid state in nature as:
- Glaciers
- Snow
- sea
- Frost
- Ice caps
- Hail
9. Reflect on the statement “Water is our responsibility before it is our right.” Share your thoughts.
Answer
The statement "Water is our responsibility before it is our right" emphasizes that access to water is a basic human right, as it is essential for drinking and other daily activities. However, with the rise in population, the demand for water is increasing. Therefore, it is crucial to use water wisely and avoid wasting it. It is also our responsibility to keep water bodies free from pollution.
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 seat of a two-wheeler parked on a sunny day can be cooled down by sprinkling water on it or keeping wet cloth on the seat. The water evaporates absorbing the heat from the seat thereby cooling it down.