Notes On Water Class Six
KEYWORDS
Precipitation: formation of raindrops, snow etc. from water vapour present in the atmosphere due to falling in temperature.
Clouds: masses of tiny droplets of water, ice particles, dust particles floating in the air.
Water pollution: the contamination of water with harmful chemicals and germs
Flood: a condition when the ground becomes submerged under water, due to heavy rain and overflowing of the river.
Drought: absence of rain in particular region for a long time leading to a severe shortage of water
Water cycle: the cyclic movement of water from the atmosphere to the earth
Evaporation: The process by which water turns into water vapour
Groundwater: the water which gets collected under the earth’s surface below the impervious rocks.
Condensation: the conversion of vapour of a substance into its liquid form by cooling
Water conservation: the phenomenon of preserving water so that it is available for the use of plants, animals and Humans rainwater harvesting: recharging the groundwater reservoirs by allowing the collected rainwater to Percolate into the ground transpiration: the process by which some water in plants evaporates into the atmosphere
Water table: the level of groundwater.
POINTS TO REMEMBER
• Water is essential for the survival of all forms of life.
• We need water for household, agricultural and industrial purposes.
• The main source of water is rain. Other sources of water are oceans, seas, rivers, lakes, pond, springs.
• Natural water is present on the surface of the earth as well as under the surface of the earth.
• A change in state from gaseous to liquid is called condensation.
• Water is universal solvent because a large number of substances can easily dissolve in it.
• The level of groundwater is known as the water table.
• An ocean is a single continuous body of salt water on the surface of the earth whereas sea is usually a smaller part of the ocean.
• When it does not rain for a year or two, we experience a drought.
• When a number of water droplets are too much, they become heavy and come down to the earth in the form of rain.
• Rain, hail and snow replenish water in rivers, lakes, ponds, wells and soil.
• The process of evaporation, transpiration, precipitation and its flow to oceans constitutes water cycle.
• The removal of the upper layer of soil is called soil erosion. Plants and trees prevent soil erosion.
• Water exists in all the three states of matter i.e. solid, liquid and gaseous.
• Water is a precious gift of nature, save water wherever you can.
• The amount of usable water on Earth is limited so it needs to be used carefully.
Multiple Choice Questions
1. The condition occurring due to no rainfall for a long period
(a) drought
(b) flood
(c) both (a) and (b)
(d) none of these
2. Plants and trees help in preventing
(a) floods
(b) rainfall
(c) snowfall
(d) all of them
3. The process by which water disappears from earth’s surface is known as
(a) evaporation
(b) condensation
(c) precipitation
(d) crystallisation
4. Which of the following is the purest form of water?
(a) oceans
(b) ponds
(c) rain
(d) sea
5. The process by which plants lose water from their leaves is called
(a) photosynthesis
(b) evaporation
(c) transpiration
(d) condensation
6. The level of groundwater is called
(a) water table
(b) water cycle
(c) hydrological cycle
(d) none of these
7. The water which is fit for human consumption is called
(a) saline water
(b) groundwater
(c) surface water
(d) potable water
8. The solid form of precipitation of water is called
(a) rain
(b) snow
(c) flood
(d) fog
Ans:
1. (a) 2. (a) 3. (a) 4. (c) 5. (c) 6. (a) 7. (d) 8. (b).
Fill in the blanks with suitable answers.
(a) Wells and springs are underground sources of———–.
(b) In our country, most of the rainfall occurs during the——– season.
(c) Water is the most important substance for the survival of life on———.
(d) The———- of groundwater is called water table.
Ans:
(a) Wells and springs are underground sources of water.
(b) In our country, most of the rainfall occurs during the monsoon season.
(c) Water is the most important substance for the survival of life on earth.
(d) The level of groundwater is called water table.
State whether true or false:
(a) No rainfall for a year or more may lead to a flood.
(b) Rainwater harvesting helps in increasing the amount of groundwater.
(c) Evaporation occurs at all temperatures.
(d) There is no shortage of drinking water during floods.
(e) Seas are larger in size than rivers.
(f) The water cycle is a natural gift to all living beings.
Ans:
(a) False, (b) True, (c) False, (d) False, (e) True (f) True
Very Short Answer Type Questions.
1. What is precipitation?
2. Name one natural source of saline water.
3. Name the process by which plants lose water.
4. Name the different states of water?
5. Why is sea water not fit for drinking and agricultural purposes?
6. Name two natural calamities.
7. We hang our wet clothes out to dry. What happens to the water in the clothes?
8. How are the animals living in soil affected, if it rains heavily?
Ans:
1. As the clouds get cooled further the water drops freeze and then fall as rain, snow or hail. This process is called precipitation.
2. Sea
3. Transpiration
4. Water vapour, water, ice or snow
5. Seawater is not fit for drinking and agricultural purposes because it is saline in nature.
6. Flood and Drought
7. The water from the clothes evaporates.
8. Heavy rains kill the animals living in soil because such animals do not get air to breathe when all the soil gets covered with flood water.